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Oracle SQL Tutorial 18 - How to Create Foreign Keys
 
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In this video we are going to be creating foreign keys. I highly recommend watching the previous video before you watch this one. Essentially, we are creating a very simple database for a system where we can create projects and add people to those projects. We started with the users table: --Delete the table if needed: --DROP TABLE users; CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); Now we are going to create a table for projects with a column that is a foreign key to the username. We're going to want to make this match data types: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) ) Next, we need to add the column attributes we decided on last video: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL ) NOT NULL because we want every project to have a creator, but we are not labeling UNIQUE because that means we could only have a specific username once in the table. We want to allow a user to create multiple projects. We also need to add a primary key: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (username) ) Now, the question that remains is, how can I tell Oracle that I want the username to reference the username column of the other table? We have to make a foreign key constraint. As you've learned from the previous videos, there are about three ways to create constraints. You can do it inline at the column level, unnamed. You can do it at the column level, named, and you can do it at the Table level, named. Usually the table-level is preferred, but I will quickly remind you how to do all three again. CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but if we want to name it, we should do this: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL CONSTRAINT projects_users_fk REFERENCES users (username), CONSTRAINT projects_pk PRIMARY KEY (project_id) ) This works, but the preferred method is to do it at the table level: CREATE TABLE projects( project_id NUMBER, project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ) Great! So you've learned how to create a foreign key, now we can see it inside of Oracle SQL Developer. One important thing when it comes to foreign keys is what happens when have data in your database and you try to delete the parent row that a row in the child table references? In the next video we are going to configure that using ON DELETE. See you all then and if you enjoy this series, please do me a huge favor by liking the video and subscribing to my YouTube channel. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 28784 Caleb Curry
How to get Parent Table, Reference Table, Foreign Key Constraint Name and Columns in SQL Server-P 71
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server Developer, you are asked to provide the query that should return all the parent tables, reference tables, Foreign Key Constraints and Columns used in Foreign Key Constraint definition. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-get-parent-table-reference-table.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 3806 TechBrothersIT
[en] SQL Developer- How to find which tables reference a given table in Oracle SQL Developer?
 
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The table can reference to one or more tables, and also be referenced by others. We are able to show it on the model tab of Oracle SQL Developer. Tiếng Việt: https://youtu.be/qhxEDL4_UY0
Views: 121 1Click2beDBA
Oracle SQL Tutorial 16 - Parent Child Relationships
 
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So far in this series we have discussed database design, creating tables, and constraints. We've brought up the concept of foreign keys, but we have not explained how to create them. That is the goal of this video and the upcoming videos. We want to study those foreign keys! Let's make them not so foreign. Let's learn the proper way to define a foreign key. As a reminder, a foreign key is a column that references a column of another table. The column it references must either be a primary key, or have the UNIQUE constraint. This means that every value inside of the column that is labeled as a foreign key, there must be that value in some row of the referenced column. As an example, imagine that we have the users table, and we have a table service_requests. We could have a column in the service_request that references a column in the users table. Usually this would be the primary key that is referenced, but there is nothing stopping you from referencing a unique column. Just for fun, let's go through an example using the username column. If we have a service_requests table, every single row within the table is going to be what some would consider an instance of a service_request. This means that the table columns are like the blueprint for what a service request looks like and then each row is an individual service request. If we have one of the columns labeled as a foreign key to the username of the users table, what does that mean practically? It means that for a single row, the value for that column must be a value that exists in the users table. We could have a service_request submitted by a user with the username of Yoloswagman. This means that there must be a row inside of the users table that has the value Yoloswagman for the username column. This brings up the concept of parent and child relationships. Yoloswagman in this situation is the parent, and his service request is the child. When we draw it out, it makes sense why a primary key must be UNIQUE. If we had two Yoloswagmans, the child would not know which column is the parent. The same applies if we were using IDs and we had So remember, always reference a primary key or a column with the UNIQUE constraint. Now, I have a question for you. Do foreign keys automatically have the UNIQUE constraint, just like primary keys? The answer is no. A parent row can have many child rows. It makes sense because the user could submit multiple service requests. Can we force the column to be unique? Absolutely. If that was the case, the user could only make one service request. Another question. Do foreign keys automatically have the NOT NULL constraint, just like primary keys? The answer is no. Essentially what this means is that a child could be created with no parent. Can we force the column to be NOT NULL? Absolutely. It is ok in some situations to allow the row to be null, but in this situation it makes no sense. It would be wise for us to add that constraint ourselves. So now that you understand some more differences between primary and foreign keys and parent child relationships, take all of these questions into consideration when you are creating foreign keys. In the next video, we are going to start a small project that is going to require multiple tables. We'll take a video to design our structure and then we'll get to creating those foreign keys in Oracle SQL Developer. Stick around and if you like these videos please be a serious supporter and subscribe to my channel. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ HELP ME! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 16044 Caleb Curry
Foreign Key in Oracle
 
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Foreign Key in Oracle oracle foreign key WHAT IS A FOREIGN KEY IN ORACLE? 1)A foreign key is a use to make referential integrity in database. 2)Foreign key values in one table must also appear in another table also. 3)The referenced table is called the parent table. 4)Table with the foreign key is called the child table. 5)The foreign key generally reference a primary key in the parent table. CREATE TABLE DEPT --- parent table ( DEPT_ID NUMERIC(10) NOT NULL, EMP_ID NUMERIC(10) NOT NULL, CONSTRAINT DEP_PK PRIMARY KEY (DEPT_ID) ); CREATE TABLE EMPLOYEE -- child table ( EMP_ID NUMERIC(10) NOT NULL, NAME VARCHAR2(50) NOT NULL, CITY VARCHAR2(50), DEPT_NO NUMERIC(10), CONSTRAINT ID_PK PRIMARY KEY (EMP_ID), CONSTRAINT FK_DEP FOREIGN KEY (DEPT_NO) REFERENCES DEPT(DEPT_ID) ); #techquerypond https://techquerypond.wordpress.com https://twitter.com/techquerypond
Views: 529 Tech Query Pond
Oracle SQL Tutorial 19 - ON DELETE (SET NULL and CASCADE)
 
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Welcome everyone! Something you need to consider when you are creating foreign keys is what happens if you delete the parent? As a reminder, the parent is the row that has the value you are referencing in the row that has a foreign key. Why is this something important to consider? It's important because foreign keys need to protect us from two primary things, unacceptable INSERT statements, and unacceptable DELETE statements. Let's see what happens when we try to insert incorrect data into the table with the foreign key: INSERT INTO projects VALUES (1, 'Update website homepage', 'CalebCurry') The response tells us plainly that there is no such user in the users table. So this works correctly. Deleting data on the other hand works a bit differently because the database does not know what you want to do with the child row when you delete the parent from the parent table. By default, we will get an error message that prevents the parent from being deleted, but there are some other options. How do we configure this? This is where the ON DELETE statement comes in. We add the keywords ON DELETE right after the foreign key and then we can give it the option of CASCADE or SET NULL. CASCADE means that if we delete the parent, we are also going to delete the child. In our situation what that means is that if somebody creates a project in our project table and then that persons account gets deleted, all of the projects he owns will also be deleted. CASCADE: CREATE TABLE projects( project_id NUMBER, Project_name VARCHAR2(50 CHAR) UNIQUE, creator VARCHAR2(50 CHAR) NOT NULL, CONSTRAINT projects_pk PRIMARY KEY (project_id), CONSTRAINT projects_users_fk FOREIGN KEY (creator) REFERENCES users (username) ON DELETE CASCADE ) SET NULL will take the value in the child table and get rid of it. What you are left with is NULL. This means that we have an orphaned child. The first thought you might have is that it is a bad thing to have an orphaned child, but in databases that is not always so. In our application if we had it set to SET NULL, when a user account gets deleted the projects would remain in existence they would just lack a creator. This might be a good thing if you are concerned about the long term survival of a project, this might be the route you want to go. It ultimately depends on the application purpose. If you don't like CASCADE or SET NULL, you can leave the entire ON DELETE statement and just have Oracle throw an error when a parent is deleted. As for us, we are going to use ON DELETE CASCADE. We need to use this with extreme caution. If you are not careful, someday you will run a delete a row and that will cascade through you database deleting a bunch of stuff you didn't want to delete. Stuff happens, so make sure you back up your database every once in eternity. Now, in the last video we started with a database design that had three tables. We've only created two in this video. In the next video we are going to create the next one, which is a little special. Then we'll finish things up by adding some indexes. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me on Patreon! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 20805 Caleb Curry
SQL Server 27 - How to Create FOREIGN KEY Constraints
 
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In the previous video we set up an entire table. The problem with this table is that the species column is just plain text. The problem with this is that there is a higher probability of incorrect data and if we have tons of animals in here there will be a lot of redundant information. The solution to this is to change this species to a foreign key to another table. Remember that when you create a foreign key it is a child to a parent. The thing you need to know is that the parent has to exist before the child so the child has something to reference. So let's create the parent table. CREATE TABLE Species( ID INT PRIMARY KEY IDENTITY, Species VARCHAR(50) NOT NULL UNIQUE, FriendlyName VARCHAR(50) NOT NULL //NOT UNIQUE because multiple rows could be same category (Ex: Bunny) ); Now, the friendly name will likely have redundant data, so maybe later we can add a table for animal categories or something, but let's not overwhelm ourselves quite yet. Maybe in a few videos. Now that we have created that table, we can recreate the table that references it. The first thing to know when creating a foreign key is that the data type must match. Because the ID column in the species table is of type INT, we should make our Species column in the Animals table also of type INT. Secondly, to make this a foreign key we add REFERENCES Species(ID) to the Species column. DROP TABLE IF EXISTS Animals; CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species INT NOT NULL REFERENCES Species(ID), ContactEmail VARCHAR(50) NOT NULL UNIQUE ); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 13382 Caleb Curry
IO5: Manipulate BFILEs with DBMS_LOB
 
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This video explores the world of BLOBs and BFILEs, from the perspective of a PL/SQL developer. Download my demo.zip from v.gd/sfdemo to access and run all referenced scripts. This video was taken from PLSQLChannel.com, originally recorded before Steven Feuerstein re-joined Oracle in March 2014. ======================================== Practically Perfect PL/SQL with Steven Feuerstein Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Database Design 17 - Parent Tables and Child Tables
 
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Donate!: http://bit.ly/DonateCTVM2. Child tables reference a primary key using a foreign key. This helps us design our relationships properly. Later in this series we will learn how the child table inherits values from the parent table and (in some instances) cannot exist without the parent (FK constraints). Learn more about parent-child tables here: https://www.calebcurry.com/blogs/database-design/parent-child-tables More content: http://CalebCurry.com Courses for Download: http://www.udemy.com/u/calebcurry/ Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Subscribe (it's free!): http://bit.ly/PqPyvH Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 32549 Caleb Curry
Oracle - SQL - Truncate Table
 
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Oracle - SQL - Truncate Table Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
Top PL/SQL Tips In Just One Hour
 
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Here's a video I recorded of a webcast to a team of developers who had one hour to spare to learn about some PL/SQL best practices. I offer tips on using compile time warnings, avoiding hard-coding/repetition, using nested subprograms and in the performance arena, lightning fast coverage of FORALL, function result cache, NOCOPY and PRAGMA UDF. Fun stuff and here's the guide: 03:00 Compile-time warnings 16:25 Don’t repeat anything 21:15 Tips on writing SQL in PL/SQL 24:50 Avoid hard-coding of formulas 28:35 Keep executable sections tiny 35:15 Avoid row-by-row processing 42:10 Function result cache 54:28 NOCOPY parameter hint 56:02 Optimizing user-defined function execution in SQL Files referenced in presentation may be found at http://www.oracle.com/webfolder/technetwork/tutorials/plsql/sfdemo.zip. But for the latest set of PL/SQL scripts, go to LiveSQL.oracle.com and search by keywords (forall, nocopy, etc.). More on PL/SQL at my blog https://stevenfeuersteinonplsql.blogspot.com PL/SQL quizzes, workouts and classes at https://devgym.oracle.com ======================================== Practically Perfect PL/SQL with Steven Feuerstein Copyright © 2018 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Foreign Key | Database Management System
 
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To ask your doubts on this topic and much more, click on this Direct Link: http://www.techtud.com/video-lecture/lecture-foreign-key IMPORTANT LINKS: 1) Official Website: http://www.techtud.com/ 2) Virtual GATE: http://virtualgate.in/login/index.php Both of the above mentioned platforms are COMPLETELY FREE, so feel free to Explore, Learn, Practice & Share! Our Social Media Links: Facebook Page: https://www.facebook.com/techtuduniversity Facebook Group: https://www.facebook.com/groups/virtualgate Google+ Page: https://plus.google.com/+techtud/posts Last but not the least, SUBSCRIBE our YouTube channel to stay updated about the regularly uploaded new videos.
Views: 289642 Techtud
Cannot truncate table because it is being referenced by a FOREIGN KEY constraint - SQL Tutorial P70
 
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SQL Server / TSQL Tutorial Scenario: You need to truncate a table but when you try to execute truncate table tableName. You get below error. Msg 4712, Level 16, State 1, Line 43 Cannot truncate table 'SchemaName.TableName' because it is being referenced by a FOREIGN KEY constraint. How would you truncate this table? Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/cannot-truncate-table-because-it-is.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 3625 TechBrothersIT
PL/SQL tutorial 76: Introduction to FORALL statement in Oracle Database
 
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RebellionRider.com presents Introduction to bulk Data processing using FORALL statement in Oracle Database by Manish Sharma ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog: http://bit.ly/forall-01 Previous Tutorial ► PL/SQL Bulk Collect with LIMIT clause ►SQL Error ORA-00942 Table or View Does Not Exist in Oracle Database http://bit.ly/ora-00942 ------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! ------------------------------------------------------------------------- ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ ___Facebook Official Page of Manish Sharma___ https://www.facebook.com/TheRebellionRider/ ___Facebook Official Page of RebellionRider.com___ https://www.facebook.com/RebellionRider.official/ You can also Email me at for E-mail address please check the About section Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 8911 Manish Sharma
Could not drop object because it is referenced by a FOREIGN KEY constraint - SQL Server P74
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server DBA or Developer, You need to drop a table from a database. When you execute drop table SchemaName.TableName statement, you get below error. Msg 3726, Level 16, State 1, Line 12 Could not drop object 'SchemaName.TableName' because it is referenced by a FOREIGN KEY constraint. Now we know that the table is referenced by Foreign Key Constraint. The problem is how to find which table has that Foreign Key Constraint that is referencing to this table. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/could-not-drop-object-because-it-is.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 3073 TechBrothersIT
sql - how to delete data from table which has self referencing foreign key column
 
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UPDATE employee SET manager_id=NULL DELETE FROM employee How to delete data from Table which has self referecing foreign key In this table Manager_Id is referring customer_id Now we try to delete data from this table Error Code: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`my_retail_data`.`employee`, CONSTRAINT `employee_fk0` FOREIGN KEY (`manager_id`) REFERENCES `employee` (`employee_id`)) to overcome, first we need set data in mangaer_id column as nulls Try, deleting data now from the Employee table Done!
Views: 908 Data Disc
IO4: Rename, Move, Copy Files with UTL_FILE
 
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UTL_FILE offers a number of high-level subprograms to perform activities like copying a file, renaming a file, and removing a file. Download my demo.zip from v.gd/sfdemo to access and run all referenced scripts. This video was taken from PLSQLChannel.com, originally recorded before Steven Feuerstein re-joined Oracle in March 2014. ======================================== Practically Perfect PL/SQL with Steven Feuerstein Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
IO6: Querying Files with the External Table Feature
 
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The external table feature of Oracle Database allows you apply SQL SELECT operations to the contents of files. Download my demo.zip from v.gd/sfdemo to access and run all referenced scripts. This video was taken from PLSQLChannel.com, originally recorded before Steven Feuerstein re-joined Oracle in March 2014. ======================================== Practically Perfect PL/SQL with Steven Feuerstein Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
SQL 12c Tutorial 22 : SQL 12c Feature TRUNCATE TABLE With CASCADE option
 
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SQL 12c Tutorial 22 : SQL 12c Feature TRUNCATE TABLE With CASCADE option SQL 12c New Features SQL 12c Tutorial for beginners Oracle SQL 12c Tutorial for beginners
Views: 1090 TechLake
IO8: Sending mail from PL/SQL with UTL_MAIL
 
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Learn how to use the UTL_MAIL package to send mail from within your PL/SQL program. Download my demo.zip from v.gd/sfdemo to access and run all referenced scripts. This video was taken from PLSQLChannel.com, originally recorded before Steven Feuerstein re-joined Oracle in March 2014. ======================================== Practically Perfect PL/SQL with Steven Feuerstein Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
MySQL 12 - Referential Integrity
 
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The concept of referential integrity is protecting relationships in our database. As a reminder, a relationship is when we have a foreign key reference another column. This column is usually the primary key of another table. This is a foreign key connection. If by any chance we establish a database structure where a table references another table, but we don't enforce this any way, the data in the table that is being referenced could be deleted, but the reference would still exist. If this happened, we would be breaking our referential integrity. We protect this by using referential constraints. A referential constraint tells the database that there is a connection between the two columns. This will allow you to configure what happens when the table being referenced gets updated or deleted. Another important thing to protecting referential integrity it to design the database in the correct way. This requires in depth knowledge of different types of relationships. How do you know when you need to put things in separate tables? We discussed all of the relationship possibilities in previous videos. In summary, relationships are not just something we assume… They are objectively defined so that the database knows they exists. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 10833 Caleb Curry
SQL Server 26 - PRIMARY KEY, NOT NULL, UNIQUE
 
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In the last video we created our first table, but I want to give SQL Server some extra information so the database knows more about each of the columns. The first thing is to establish the primary key. To do this all we do is add PRIMARY KEY after the column we want to be the primary key. Simple enough. When we add a constraint right after the column like this, it is often called a column attribute. CREATE TABLE Animals( ID INT PRIMARY KEY, Name VARCHAR(50), Species VARCHAR(50) ); Additionally, if you are using an ID column, it is best to have it labeled as the IDENTITY column. That way, SQL Server will automatically increment the number. CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50), Species VARCHAR(50) ); The other attributes we've discussed in this series are NOT NULL and UNIQUE. We can make the name NOT NULL and the species NOT NULL. We don't have a good column for UNIQUE, so let's add one: CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species VARCHAR(50) NOT NULL, ContactEmail VARCHAR(50) NOT NULL UNIUQE ); You can see that it is very easy to add multiple column attributes to a column. Just separate them by spaces. The order does not matter. Also, when you say primary key the column is automatically NOT NULL and UNIQUE. There are other attributes you can use including DEFAULT, FOREIGN KEY, and SPARSE. DEFAULT will give a value for a column if you do not put anything in yourself. Foreign keys are used to reference other columns. SPARSE is an attribute we haven't discussed. You can use SPARSE if most of the rows are going to have a NULL for a column and it saves storage space, but we will worry about that in another video. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 6964 Caleb Curry
SQL Constraints - NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default
 
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SQL is a standard Structured query language for storing, manipulating and retrieving data in databases. NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default 1) NOT NULL - Ensures that a column cannot have a NULL value 2) UNIQUE - Ensures that all values in a column are different 3) PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Uniquely identifies each row in a table 4) FOREIGN KEY - Uniquely identifies a row/record in another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. prevents invalid data and destroy links between tables. 5) CHECK - Ensures that all values in a column satisfies a specific condition 6) DEFAULT - Sets a default value for a column when no value is specified 7) INDEX - Used to create and retrieve data from the database very quickly.
Views: 70 R K
SQL Tutorial - 13: Inserting Data Into a Table From Another Table
 
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In this tutorial we'll learn to use the INSERT Query to copy data from one table into another.
Views: 280878 The Bad Tutorials
PL/SQL Tutorial | Exception Handling in Oracle Database
 
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Learn exception handling in oracle, understanding different types of exceptions and trapping exception with SQLERRM and SQLCODE. How to handle exception in oracle database, How to handle user defined exception in oracle database, What is Pragma in Exception Handling, What is Pragma Exception_INIT in oracle, Difference between named and unnamed exception in oracle, Types of exception available in oracle, How to use Raise_application_error in oracle, How to use custom exception in oracle, Details of System Exception: DUP_VAL_ON_INDEX ORA-00001 You tried to execute an INSERT or UPDATE statement that has created a duplicate value in a field restricted by a unique index. TIMEOUT_ON_RESOURCE ORA-00051 You were waiting for a resource and you timed out. TRANSACTION_BACKED_OUT ORA-00061 The remote portion of a transaction has rolled back. INVALID_CURSOR ORA-01001 You tried to reference a cursor that does not yet exist. This may have happened because you've executed a FETCH cursor or CLOSE cursor before OPENing the cursor. NOT_LOGGED_ON ORA-01012 You tried to execute a call to Oracle before logging in. LOGIN_DENIED ORA-01017 You tried to log into Oracle with an invalid username/password combination. NO_DATA_FOUND ORA-01403 You tried one of the following: You executed a SELECT INTO statement and no rows were returned. You referenced an uninitialized row in a table. You read past the end of file with the UTL_FILE package. TOO_MANY_ROWS ORA-01422 You tried to execute a SELECT INTO statement and more than one row was returned. ZERO_DIVIDE ORA-01476 You tried to divide a number by zero. INVALID_NUMBER ORA-01722 You tried to execute a SQL statement that tried to convert a string to a number, but it was unsuccessful. STORAGE_ERROR ORA-06500 You ran out of memory or memory was corrupted. PROGRAM_ERROR ORA-06501 This is a generic "Contact Oracle support" message because an internal problem was encountered. VALUE_ERROR ORA-06502 You tried to perform an operation and there was a error on a conversion, truncation, or invalid constraining of numeric or character data. CURSOR_ALREADY_OPEN ORA-06511 You tried to open a cursor that is already open. Linkedin: https://www.linkedin.com/in/aditya-kumar-roy-b3673368/ Facebook: https://www.facebook.com/SpecializeAutomation/
Views: 1348 Specialize Automation
PLS-22: Using Parameters in PL/SQL Procedure
 
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Parameters in PL/SQL Procedure For Full Course Experience Please Go To http://mentorsnet.org/course_preview?course_id=5 Full Course Experience Includes 1. Access to course videos and exercises 2. View & manage your progress/pace 3. In-class projects and code reviews 4. Personal guidance from your Mentors
Views: 39058 Oresoft LWC
MySQL - How to Add Foreign Key Constraints by Workbench
 
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There're two parts in this video to demonstrate how to add foreign key constraints in MySQL by Workbench. Part 1. Adding a foreign referencing constraint. The parent column is "categories"."id" and the child column is "items"."category_id" which is in another table. Part 2. Adding a self referencing constraint. The parent column is "categories"."id" and the child column is "categories"."parent_id" which is in the same table. No matter what type of referencing constraint that you want to add, the steps are all the same: 1. Make sure the parent column has been indexed. 2. Create an index for the child column. 3. Add a referencing constraint on the child column. 4. Check whether the result of the constraint is made. If you met errors something like "error 1215 (hy000): cannot add foreign key constraint" while adding a foreign key, you may refer to this post below: http://logic.edchen.org/how-to-resolve-mysql-error-1215-hy000-cannot-add-foreign-key-constraint/
Views: 8927 House of Click
Tutorial#11 How to Truncate Table in Oracle SQL database by rakesh malviya
 
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Tutorial How to truncate table in Oracle database, delete data in one shot in Oracle SQL Oracle SQL Practice Question : https://drive.google.com/open?id=1SekH0DL5zg0eTsG0lZ4JUHaLTEJDdcVN In this series we cover the following topics: SQL basics, create table oracle, SQL functions, SQL queries, SQL server, SQL developer installation, Oracle database installation, SQL Statement, OCA, Data Types, Types of data types, SQL Logical Operator, SQL Function,Join- Inner Join, Outer join, right outer join, left outer join, full outer join, self-join, cross join, View, SubQuery, Set Operator. follow me on: Facebook Page: https://www.facebook.com/LrnWthr-319371861902642/?ref=bookmarks Contacts Email: [email protected] Instagram: https://www.instagram.com/lrnwthr/ Twitter: https://twitter.com/LrnWthR
Views: 292 EqualConnect Coach
SQL script to insert into many to many table
 
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Text Article http://csharp-video-tutorials.blogspot.com/2017/02/sql-script-to-insert-into-many-to-many.html Slides http://csharp-video-tutorials.blogspot.com/2017/02/sql-script-to-insert-into-many-to-many_6.html SQL Server Interview Questions and Answers text articles & slides http://csharp-video-tutorials.blogspot.com/2014/05/sql-server-interview-questions-and.html SQL Server Interview Questions and Answers playlist https://www.youtube.com/playlist?list=PL6n9fhu94yhXcztdLO7i6mdyaegC8CJwR All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists In this video we will discuss how to insert data into a table that has many-to-many relationship Create table Students ( Id int primary key identity, StudentName nvarchar(50) ) Go Create table Courses ( Id int primary key identity, CourseName nvarchar(50) ) Go Create table StudentCourses ( StudentId int not null foreign key references Students(Id), CourseId int not null foreign key references Courses(Id) ) Go Students - Id column is identity column Courses - Id column is identity column StudentCourses - StudentId and CourseId columns are foreign keys referencing Id column in Students and Courses tables As you can see, StudentCourses is a bridge table that has many to many relationship with Students and Courses tables. This means a given student can be enrolled into many courses and a given course can have many students enrolled. Below is the question asked in an interview for SQL Server Developer role. Write a SQL script to insert data into StudentCourses table. Here are the rules that your script should follow. 1. There will be 2 inputs for the script Student Name - The name of the student who wants to enroll into a course Course Name - The name of the course the student wants to enroll into 2. If the student is already in the Students table, then use that existing Student Id. If the student is not already in the Students table, then a row for that student must be inserted into the Students table, and use that new student id. 3. Along the same lines, if the course is already in the Courses table, then use that existing Course Id. If the course is not already in the Courses table, then a row for that course must be inserted into the Courses table, and use that new course id. 4. There should be no duplicate student course enrollments, i.e a given student must not be enrolled in the same course twice. For example, Tom must not be enrolled in C# course twice. Answer : To avoid duplicate student course enrollments create a composite primary key on StudentId and CourseId columns in StudentCourses table. With this composite primary key in place, if someone tries to enroll the same student in the same course again we get violation of primary key constraint error. Alter table StudentCourses Add Constraint PK_StudentCourses Primary Key Clustered (CourseId, StudentId) Here is the SQL script that inserts data into the 3 tables as expected Declare @StudentName nvarchar(50) = 'Sam' Declare @CourseName nvarchar(50) = 'SQL Server' Declare @StudentId int Declare @CourseId int -- If the student already exists, use the existing student ID Select @StudentId = Id from Students where StudentName = @StudentName -- If the course already exists, use the existing course ID Select @CourseId = Id from Courses where CourseName = @CourseName -- If the student does not exist in the Students table If (@StudentId is null) Begin -- Insert the student Insert into Students values(@StudentName) -- Get the Id of the student Select @StudentId = SCOPE_IDENTITY() End -- If the course does not exist in the Courses table If (@CourseId is null) Begin -- Insert the course Insert into Courses values(@CourseName) -- Get the Id of the course Select @CourseId = SCOPE_IDENTITY() End -- Insert StudentId & CourseId in StudentCourses table Insert into StudentCourses values(@StudentId, @CourseId) If required, we can very easily convert this into a stored procedure as shown below. Create procedure spInsertIntoStudentCourses @StudentName nvarchar(50), @CourseName nvarchar(50) as Begin Declare @StudentId int Declare @CourseId int Select @StudentId = Id from Students where StudentName = @StudentName Select @CourseId = Id from Courses where CourseName = @CourseName If (@StudentId is null) Begin Insert into Students values(@StudentName) Select @StudentId = SCOPE_IDENTITY() End If (@CourseId is null) Begin Insert into Courses values(@CourseName) Select @CourseId = SCOPE_IDENTITY() End Insert into StudentCourses values(@StudentId, @CourseId) End Use the following statement to execute the stored procedure Execute spInsertIntoStudentCourses 'Tom','C#'
Views: 103851 kudvenkat
How to Drop Foreign Key Constraint in SQL Server Database - SQL Server / TSQL Tutorial Part 75
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer and you need to prepare the script to drop the Foreign Key Constraint which was created on dbo.Orders table. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-drop-foreign-key-constraint-in.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 4764 TechBrothersIT
Excel Magic Trick 1349: Power Query with Input Variables from Excel Sheet to Extract Records
 
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Download File: http://people.highline.edu/mgirvin/excelisfun.htm See how to use Power Query (Get & Transform) with Input Variables from Excel Sheet to Extract Records and create a Revenue Report. Here are the steps: 1. (00:15) Introduction including Preview of Finished Solution and Preview of steps necessary to accomplish this goal. 2. (02:00) Import and transform Data Set, including removing Columns, Filter For Records and adding an extra Column to calculate Net Revenue using the Number.Round Power Query Function. 3. (06:38) Load Report to Sheet 4. (07:09) Import each Parameter/Criteria Table. 5. (07:36) Convert each Criteria Table to a single Text Item using the Record.Field Power Query Function. 6. (11:38) Declare and Insert Variables into M Code for Report 7. (14:10) Test Reporting System 8. (14:30) Create Recorded Macro To Refresh All and assign it to a Form button 9. (16:40) Test Macro and Reporting System 10. (17:25) Summary
Views: 96094 ExcelIsFun
How to create Virtual Columns in Oracle Database
 
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How to create Virtual Columns in Oracle Database 12c When queried, virtual columns appear to be normal table columns, but their values are derived rather than being stored on disc. The syntax for defining a virtual column is listed below. column_name [datatype] [GENERATED ALWAYS] AS (expression) [VIRTUAL] If the datatype is omitted, it is determined based on the result of the expression. The GENERATED ALWAYS and VIRTUAL keywords are provided for clarity only. The script below creates and populates an employees table with two levels of commission. It includes two virtual columns to display the commission-based salary. The first uses the most abbreviated syntax while the second uses the most verbose form. CREATE TABLE employees ( id NUMBER, first_name VARCHAR2(10), last_name VARCHAR2(10), salary NUMBER(9,2), comm1 NUMBER(3), comm2 NUMBER(3), salary1 AS (ROUND(salary*(1+comm1/100),2)), salary2 NUMBER GENERATED ALWAYS AS (ROUND(salary*(1+comm2/100),2)) VIRTUAL, CONSTRAINT employees_pk PRIMARY KEY (id) ); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (1, 'JOHN', 'DOE', 100, 5, 10); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (2, 'JAYNE', 'DOE', 200, 10, 20); COMMIT; Querying the table shows the inserted data plus the derived commission-based salaries. SELECT * FROM employees; ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 SALARY2 ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- 1 JOHN DOE 100 5 10 105 110 2 JAYNE DOE 200 10 20 220 240 2 rows selected. SQL The expression used to generate the virtual column is listed in the DATA_DEFAULT column of the [DBA|ALL|USER]_TAB_COLUMNS views. COLUMN data_default FORMAT A50 SELECT column_name, data_default FROM user_tab_columns WHERE table_name = 'EMPLOYEES'; COLUMN_NAME DATA_DEFAULT ------------------------------ -------------------------------------------------- ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 ROUND("SALARY"*(1+"COMM1"/100),2) SALARY2 ROUND("SALARY"*(1+"COMM2"/100),2) 8 rows selected. SQL Notes and restrictions on virtual columns include: 1)Indexes defined against virtual columns are equivalent to function-based indexes. 2)Virtual columns can be referenced in the WHERE clause of updates and deletes, but they cannot be manipulated by DML. 3)Tables containing virtual columns can still be eligible for result caching. 4)Functions in expressions must be deterministic at the time of table creation, but can subsequently be recompiled and made non-deterministic without invalidating the virtual column. In such cases the following steps must be taken after the function is recompiled: a)Constraint on the virtual column must be disabled and re-enabled. b)Indexes on the virtual column must be rebuilt. c)Materialized views that access the virtual column must be fully refreshed. d)The result cache must be flushed if cached queries have accessed the virtual column. e)Table statistics must be regathered. 5)Virtual columns are not supported for index-organized, external, object, cluster, or temporary tables. 6)The expression used in the virtual column definition has the following restrictions: a.It cannot refer to another virtual column by name. b.It can only refer to columns defined in the same table. c.If it refers to a deterministic user-defined function, it cannot be used as a partitioning key column. e.The output of the expression must be a scalar value. It cannot return an Oracle supplied datatype, a user-defined type, or LOB or LONG RAW.
Views: 610 OracleDBA
PL/SQL Tutorial | User Defined Exception | Pragma Exception_INIT in Oracle Database 11g
 
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Learn in depth with example about creating user defined exception using Pragma Exception_INIT and Raise_application_error following handling of different types of system named and unnamed exception in details. How to handle exception in oracle database, How to handle user defined exception in oracle database, What is Pragma in Exception Handling, What is Pragma Exception_INIT in oracle, Types of exception available in oracle, How to use Raise_application_error in oracle, How to use custom exception in oracle, How to use pragma autonomous transaction, SQLERRM, SQLCODE, Raise_application_error, In Oracle PL/SQL, PRAGMA refers to a compiler directive or "hint" it is used to provide an instruction to the compiler. The 5 types of Pragma directives available in Oracle are listed below: * PRAGMA AUTONOMOUS_TRANSACTION * PRAGMA SERIALLY_REUSABLE * PRAGMA RESTRICT_REFRENCES * PRAGMA EXCEPTION_INIT * PRAGMA INLINE Details of System Exception: DUP_VAL_ON_INDEX ORA-00001 You tried to execute an INSERT or UPDATE statement that has created a duplicate value in a field restricted by a unique index. TIMEOUT_ON_RESOURCE ORA-00051 You were waiting for a resource and you timed out. TRANSACTION_BACKED_OUT ORA-00061 The remote portion of a transaction has rolled back. INVALID_CURSOR ORA-01001 You tried to reference a cursor that does not yet exist. This may have happened because you've executed a FETCH cursor or CLOSE cursor before OPENing the cursor. NOT_LOGGED_ON ORA-01012 You tried to execute a call to Oracle before logging in. LOGIN_DENIED ORA-01017 You tried to log into Oracle with an invalid username/password combination. NO_DATA_FOUND ORA-01403 You tried one of the following: You executed a SELECT INTO statement and no rows were returned. You referenced an uninitialized row in a table. You read past the end of file with the UTL_FILE package. TOO_MANY_ROWS ORA-01422 You tried to execute a SELECT INTO statement and more than one row was returned. ZERO_DIVIDE ORA-01476 You tried to divide a number by zero. INVALID_NUMBER ORA-01722 You tried to execute a SQL statement that tried to convert a string to a number, but it was unsuccessful. STORAGE_ERROR ORA-06500 You ran out of memory or memory was corrupted. PROGRAM_ERROR ORA-06501 This is a generic "Contact Oracle support" message because an internal problem was encountered. VALUE_ERROR ORA-06502 You tried to perform an operation and there was a error on a conversion, truncation, or invalid constraining of numeric or character data. CURSOR_ALREADY_OPEN ORA-06511 You tried to open a cursor that is already open. Linkedin: https://www.linkedin.com/in/aditya-kumar-roy-b3673368/ Facebook: https://www.facebook.com/SpecializeAutomation/
SQL Server 28 - Composite Primary Key
 
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The previous video had these tables: CREATE TABLE Species( ID INT PRIMARY KEY IDENTITY, Species VARCHAR(50) NOT NULL UNIQUE, FriendlyName VARCHAR(50) NOT NULL ); CREATE TABLE Animals( ID INT PRIMARY KEY IDENTITY, Name VARCHAR(50) NOT NULL, Species INT NOT NULL REFERENCES Species(ID), ContactEmail VARCHAR(50) NOT NULL UNIQUE ); These column attributes are all examples of constraints. To be more specific, they are known as column-level constraints. Sometimes you need to create what is known as a table-level constraint. To illustrate this, we are going to create a new table that shows this in action. Remember that we are trying to create an animal dating site. A specific animal can create an account on our website and say what kind of species he or she is interested in. One specific animal can be interested in multiple species and an individual species can be liked by many animals. Therefore, it is a many to many relationship. We already have a Species table and an Animals table, so we need an intermediary table to associate animals with species: CREATE TABLE Interests( AnimalID INT NOT NULL REFERENCES Animals(ID), SpeciesID INT NOT NULL REFERENCES Species(ID) ); But now, we want to create a composite primary key, the combination of both columns. A column-level attribute is not capable of doing this because it is associated with just one column. Let's create a table-level constraint. To do this we add the constraint as if it's another column: CREATE TABLE Interests( AnimalID INT NOT NULL REFERENCES Animals(ID), SpeciesID INT NOT NULL REFERENCES Species(ID), PRIMARY KEY (AnimalID, SpeciesID) ); The downside here is that we cannot create a foreign key to reference this composite key. If for some reason we have to be able to reference an individual interest in another table, we would create an ID column and put a UNIQUE constraint on the combination of AnimalID and SpeciesID. Then we could reference an individual ID. Now, in SSMS, inside of our tables key folder you can find the composite key. Unfortunately, SSMS defaults to a pretty ugly name for our primary key constraint. Fortunately, we can actually give names to our constraints. That's what we will be doing in the next video. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 14961 Caleb Curry
Constraints Part-2 NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default
 
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SQL is a standard Structured query language for storing, manipulating and retrieving data in databases. NOT NULL , UNIQUE , PRIMARY KEY , FOREIGN KEY , CHECK , INDEX , default 1) NOT NULL - Ensures that a column cannot have a NULL value 2) UNIQUE - Ensures that all values in a column are different 3) PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Uniquely identifies each row in a table 4) FOREIGN KEY - Uniquely identifies a row/record in another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. prevents invalid data and destroy links between tables. 5) CHECK - Ensures that all values in a column satisfies a specific condition 6) DEFAULT - Sets a default value for a column when no value is specified 7) INDEX - Used to create and retrieve data from the database very quickly.
Views: 65 R K
Difference Between Delete and Truncate
 
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Below is link for Useful Pl/SQL Books http://goo.gl/XMy0tt ---------------------------------------------------------- Difference Between Delete and Truncate in Detail On bigger picture they serve the same purpose but there are many Differences listed with examples Point Delete Truncate 1. Data Recovery Delete: Come under the DML Category, we need to commit or Rollback explicitly to make the changes permanent, so we can recover the data by Rollback command fully with in a session or up to a point if Save Points are used Fall In DDL Category (DDL Command issue the Auto commit implicitly) so no chances of Recovery even not using the Flashback table method. But Truncate operations are also logged , they didn’t generate redo SQL but they are logged , view for truncated data info V$LOGMNR_CONTENTS 2. Data Removal Delete Can remove all or selected data using the Where Clause predicates. Or we can say delete any subset of rows We can Truncate complete table or a partition or sub partition of a table. 3. Speed Delete is Slower because oracle maintain the redo logs for Read Consistency (so that every session connected can see a consistent data at a given point of time ) Delete is very time consuming activity especially when table have numerous indexes and Triggers associated with table Faster as no data logs are maintained no associated trigger firing. 4. DML Triggers Firing DML (Delete) triggers associated with table will fire. DML Trigger will not fire in case of truncate method. 5. Flashback Technology Data can be recovered even after commit operation using Flashback Table options Flashback_transaction_query table will give what to recover and up to which point. Data cannot be recovered in truncate method by Flashback table option. 6. Referential Integrity Constraint Behavior if we don’t have related data in child table then we can delete the data from the parent table or we have variants like On Delete Cascade & on Delete set Null. We can’t truncate a table with enable Referential Integrity Constraint, even there is no data in the child table, we have to disable or drop the constraint if we want to truncate the table. Exception: Truncate is possible if the FK is self-referential means primary key and foreign key are on the same table. 7. Space De allocation or Space Utilization No extent reset with delete when deleting rows from a table, extents are not de allocated, So if there were 50 extents in the table before the deletion, there will still be 50 after the deletion. Truncate: When a table is truncated it will free the space allocated except in case of reuse storage clause. This space can subsequently be used only by new data in the table or cluster resulting from insert or update operations .All extents are de allocated leaving only the extents specified when the table was originally created .Example So if the table was originally created with min extents 3, there will be 3 extents remaining when the tables is truncated. When you truncate a table, NEXT is automatically reset to the last extent deleted. 8. High Water Mark Delete will not reset the high water mark Truncate will reset the High Water mark which is very important for performance point of view as in case of full table scan and full index scan oracle will read all the block under high water mark this makes a lot of difference in terms of performance. 9. Cluster No as such restriction with delete. You cannot individually truncate a table that is part of a cluster. You must truncate the cluster, Delete all rows from the table, or drop and re-create the table. 10. Information Capturing Delete : we can capture the row information what we have deleted using Delete Method, f you are deleting multiple records then use composite data types (collections & records) Truncate Don’t have this feature of capturing the deleted records. 11. Function Based Index Impact DELETE You cannot delete rows from a table if a function-based index on the table has become invalid. You must first validate the function-based index. Truncate: No as such restriction 12. UNUSABLE Indexes Delete no as such feature. Truncate if table is not empty then truncate make all unusable indexes to useable. 13. Complex views You cannot delete data from a Complex view except through INSTEAD OF triggers. But we can delete data from simple Views and MV. We cannot truncate a view simple or complex but you can truncate MV with special Features like Preserve MV Logs and Purge MV Logs. 14. Privileges Delete You need to provide delete table privilege on object. Truncate you must have drop table privilege there is no truncate table privilege exists. 15. Domain Index No as such restriction You cannot truncate the object having domain index in invalid or In progress state
Views: 14352 Ram Gupta
Public and Private Synonyms
 
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What are private and public synonyms and how do they work? And what privileges do they convey onto the objects that are referenced by them? Highlights from my Office Hours session blog: https://connor-mcdonald.com twitter: https://twitter.com/connor_mc_d Subscribe for new tech videos every week music: bensound.com
Views: 454 Connor McDonald
Oracle 12c PL/SQL Security New Features - Session 6 of 8 - Granting Roles to Procedures
 
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See www.skillbuilders.com/12c-plsql-security for all free modules in this tutorial. It is now in Oracle Database 12c possible to grant roles to the stored program units. Remember this didn't apply to anonymous PL/SQL. Anonymous PL/SQL as always executed with the enabled roles of the invoker. But we can now grant role to a stored procedure. There are a couple of conditions. The role granted must be directly granted to the owner. I'm not sure if this is documented or not or it could've been issues I had during my own testing but certainly the last time I tested this thoroughly I found that if I granted roles to roles to roles to roles as I go down to three, it no longer functions. So that could've been just me or it may be documented. But certainly to be sure, the role granted must be granted directly to the person who's writing the code. Also and it is documented, the owner still needs direct privileges on the object that the code references. That make perfect sense because the role might be disabled at the time that he happens to be creating the object. So you need the role, you need direct privileges on the object referenced by the code. [pause] The invoker however needs absolutely nothing. The invoker now needs nothing, no roles, no privileges. All he needs is execute on the procedure. The invoker will then take on that role during the course of the call. This will tighten up the definer's rights problem and that our user doesn't have much at all. He needs the bare minimum and then only that role will be available, only the role is available to the invoker during the call. Not everything else that the owner happens to have. You can combine this as well with invoker's rights and either way we are controlling privilege inheritance. Invoker's rights plus roles restrict the ability of definer's to inherit privileges from invokers and invokers inherits privileges from definers, both of which raise that ghastly possibility of privilege escalation associated typically to SQL injection. [pause] Grant create session, create procedure to dev, and that will give him select on scott.emp to dev. I've given dev the minimum he needs to write code that hits that table. Then create a role. [pause] Create role r1 and that'll grant select on scott.emp to r1. Finally, grant r1 to dev. It has met the requirements. The role is granted to the owner, the owner does have direct privileges. [pause] So connect as dev/dev and create my favorite procedure. [pause] The same procedure has executed definer's rights and query scott.emp. But now what we can do this new is I can grant r1 to procedure list_emp. [pause] I'll create a very low privileged user now. I need to connect as sysdba and create user low identified by low, and all I shall give him is create session. [pause] And execute on that procedure. [pause] Grant execute on dev.list_emp to low. That's all he's got. He can log on and he can run, run one procedure. What actually is going to happen to him? Let me try to log on. Connect sys low/low set server output on and see if he can run that thing. Just to check, if he tries to select star from scott.emp he is the lowest of the low is my user low. But then execute dev.list_emp, trying to retrieve the CLARKs and it works. And because my user low has virtually no privileges at all, there's no possible danger of the malicious developer being able to inherit dangerous privileges from him. [pause] The final step, that functioned because of the privilege that I mentioned earlier - the privilege that we saw on the previous slide which was inheriting privileges. If I revoke that - and this is what you should be doing in all your systems after upgrade - revoke inherit privileges on user low from public, connect there, and it fails. So the final bit of tightening up the security is to grant the privilege specifically we grant inherit privileges on user low to dev. Now we have a totally secure system and that my low privilege user dev can do that. [pause] And nothing more. My low privileged developer dev can't grab anything in his too as well. That tightens things up totally.
Views: 2930 SkillBuilders
IO7: Sending Text to Screen with DBMS_OUTPUT
 
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This video explores the DBMS_OUTPUT package, which directs text to system output (your screen). Download my demo.zip from v.gd/sfdemo to access and run all referenced scripts.
Example on foreign key constraint and delete cascade
 
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Join discussion on http://www.techtud.com/video-illustration/following-table-has-two-attributes-and-c-where-primary-key-and-c-foreign-gate
Views: 9565 Techtud
TSQL: "Cannot DROP TABLE Table because it is being referenced by view View"
 
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Solving "Cannot DROP TABLE tblOurTable because it is being referenced by view_OurView."
Views: 86 SQLInSix Minutes
Create, Alter, Drop foreign Key constraint in SQL Server - Part 14
 
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Subscribe to IT PORT : https://www.youtube.com/c/itport28 SQL Server Tutorial in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ64enJDwWVvN3KduuZRlUrb3 SQL Server Concepts in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ67kdNIByJKAGBIBhor_h4Hs SQL Server Analytic Functions in Tamil : https://www.youtube.com/playlist?list=PLouAaeZ4xQ65XIU5azEUgLVrBKEl-jWMV SQL Server Tutorial : https://www.youtube.com/playlist?list=PLouAaeZ4xQ66AYrzPtxt2SeeR4UABcBcO SQL Server Concepts : https://www.youtube.com/playlist?list=PLouAaeZ4xQ66zRe8-nDDy-YHY2o0rmbn4 SQL Server Analytic Functions : https://www.youtube.com/playlist?list=PLouAaeZ4xQ64hTsEdhLsVBquE1vERWngX A foreign key (FK) is a column or combination of columns that is used to establish and enforce a link between the data in two tables. You can create a foreign key by defining a FOREIGN KEY constraint when you create or modify a table. In a foreign key reference, a link is created between two tables when the column or columns that hold the primary key value for one table are referenced by the column or columns in another table. This column becomes a foreign key in the second table. A table can have 253 foreign key constraints.
Views: 349 IT Port
Difference between delete and truncate - Interview question | OrclData
 
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RUNCATE TRUNCATE is a DDL command TRUNCATE is executed using a table lock and whole table is locked for remove all records. We cannot use Where clause with TRUNCATE. TRUNCATE removes all rows from a table. Minimal logging in transaction log, so it is performance wise faster. TRUNCATE TABLE removes the data by deallocating the data pages used to store the table data and records only the page deallocations in the transaction log. Identify column is reset to its seed value if table contains any identity column. To use Truncate on a table you need at least ALTER permission on the table. Truncate uses the less transaction space than Delete statement. Truncate cannot be used with indexed views. DELETE DELETE is a DML command. DELETE is executed using a row lock, each row in the table is locked for deletion. We can use where clause with DELETE to filter & delete specific records. The DELETE command is used to remove rows from a table based on WHERE condition. It maintain the log, so it slower than TRUNCATE. The DELETE statement removes rows one at a time and records an entry in the transaction log for each deleted row. Identity of column keep DELETE retain the identity. To use Delete you need DELETE permission on the table. Delete uses the more transaction space than Truncate statement. Delete can be used with indexed views.
Views: 84 ANKUSH THAVALI
SQL Server 12 - Referential Integrity
 
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The concept of referential integrity is protecting relationships in our database. As a reminder, a relationship is when we have a foreign key reference another column. This column is usually the primary key of another table. This is a foreign key connection. If by any chance we establish a database structure where a table references another table, but we don't enforce this any way, the data in the table that is being referenced could be deleted, but the reference would still exist. If this happened, we would be breaking our referential integrity. We protect this by using referential constraints. A referential constraint tells the database that there is a connection between the two columns. This will allow you to configure what happens when the table being referenced gets updated or deleted. Another important thing to protecting referential integrity it to design the database in the correct way. This requires in depth knowledge of different types of relationships. How do you know when you need to put things in separate tables? We discussed all of the relationship possibilities in previous videos. In summary, relationships are not just something we assume… They are objectively defined so that the database knows they exists. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Support me! http://www.patreon.com/calebcurry Subscribe to my newsletter: http://bit.ly/JoinCCNewsletter Donate!: http://bit.ly/DonateCTVM2. ~~~~~~~~~~~~~~~Additional Links~~~~~~~~~~~~~~~ More content: http://CalebCurry.com Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://twitter.com/calebCurry Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 12432 Caleb Curry
Truncate Table With Foreign Key
 
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Truncate Table A Table With Foreign Key In SQL Server.
Views: 931 Pramadha just fun
How to Implement ON DELETE CASCADE in Oracle 10g Database.
 
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Hello Friends, In this Video we will learn ON DELETE CASCADE keyword. We will be create two tables called 1) dept(Department) and emp(Employee). Here, dept table will serve as Parent table and emp table will serve as child table. We will then add Foreign key Constraint at Child table. we will then populate the data in Parent table and child table. Our primary purpose is when i delete a particular record from my parent table (i.e. department table/dept) then referenced record (i.e. a record that is referred in child table should delete). This is the concept of ON DELETE CASCADE i.e you delete a record from parent table and a concerened record from child table will delete. Thank you for Watching. Subscribe my Channel for more videos on Database.
Views: 40 Hardik Parmar
How to Create Foreign Key Constraint with ON DELETE SET NULL Option in SQL Server -SQL Server P81
 
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SQL Server / T-SQL Tutorial Scenario: You are working as SQL Server developer, you need to create two tables with Primary -Foreign Key Relationship. You want to create Foreign Key Constraint with setting if record will be deleted from Referenced Table (Primary Key Column Table), it should not be deleted from Parent Table ( Foreign Key Constraint Table) instead the value should be updated to Null. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint_95.html Check out our website for Different SQL Server, MSBI tutorials and interview questions such as SQL Server Reporting Services(SSRS) Tutorial SQL Server Integration Services(SSIS) Tutorial SQL Server DBA Tutorial SQL Server / TSQL Tutorial ( Beginner to Advance) http://www.techbrothersit.com/
Views: 1056 TechBrothersIT
MySQL- Delete Record from Database
 
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Get Source Code/Read : http://intactabode.com/ For Developing support email your Details at : [email protected] Install Free Trail GST Ready Accounting Package Send your Contact information Name, Email, Contact Number to watch demo in English : https://www.youtube.com/watch?v=a4sFNtZuYzs&ab_channel=IntactAbode watch demo in Hindi : https://www.youtube.com/watch?v=I3eCieDpG3o&ab_channel=IntactAbode For Source Code Visit : http://corneey.com/wJ6X2K Subscribe to YouTube channel http://corneey.com/wJ6VoC Like us on Facebook http://corneey.com/wJ6C2l Follow us on Twitter http://corneey.com/wJ6C7x Follow me on Google+ http://corneey.com/wJ6Vhc linkedin http://corneey.com/wJ6V5g Watch More Frequently Used Sql Queries in all Databases Complete Playlist: https://www.youtube.com/playlist?list=PLErD1cRL87W992bgZ_TX7gxl5UKuP9yF9 truncate table sql delete table mysql sql delete column sql delete join sql delete multiple rows delete all rows from table mysql delete query in oracle the delete statement conflicted with the reference constraint
Views: 355 Intact Abode