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SQL tutorials 20: On Delete Cascade Foreign Key By Manish Sharma (RebellionRider)
 
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Oracle Database 11g Tutorial 20: On delete cascade This tutorial will show you how to define foreign key with on delete cascade clause. Links Blog: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 On delete set Null: http://www.rebellionrider.com/on-delete-cascade.htm SQL Tutorial 19 Foreign Key: http://youtu.be/0nbkBI5r3Gw Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com
Views: 46195 Manish Sharma
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: 17473 Caleb Curry
Oracle 12c New Feature On Delete Cascade
 
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oracle 12c new features for developers Oracle 12c New Feature On Delete Cascade
Views: 269 Siva Academy
113. ON DELETE CASCADE in SQL (Hindi)
 
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Views: 9633 Geeky Shows
Oracle Database Constraints ON DELETE CASCADE & more
 
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Oracle Database Constraints ON DELETE CASCADE /ON DELETE set null maxvlearn.com
Views: 594 khaled alkhudari
ON DELETE CLAUSE OF FOREIGN KEY CONSTRAINT IN ORACLE SQL WITH EXAMPLE (CASCADE/SET NULL/NO ACTION)
 
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This is a free video tutorial explaining about the nonmandatory on delete clause in the foreign key constraint in Oracle SQL database, the video explains about how the on delete set null and on delete cascade works, how it can be implemented with easy to understand examples. We have also shown practical demonstration on creating the foreign key constraint, and then deleting the data from the parent table and observing the changes that take place in the child table.
Views: 1496 Kishan Mashru
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: 8803 Techtud
MySQL 17 - ON DELETE and ON UPDATE
 
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Now, what happens when you have successfully created a reference, and now you try deleting the parent? This is where the ON DELETE clause come in. This is essentially how we configure how strict a foreign key is. There are 3 options you can give for an ON DELETE: RESTRICT / NO ACTION Yes - In MySQL they are the same, but not all DBMS. CASCADE Yes SET NULL Yes Now the default is RESTRICT. This means that when you try to delete a parent row, MySQL is going to throw an error and not let you. Cascade means that if you delete the parent row, any rows that reference that parent will also be deleted. This is pretty dangerous and not often recommended. SET NULL will set the foreign key to be NULL. Now obviously, this is going to require that the foreign key is not labelled NOT NULL. In addition to the ON DELETE clause, there is the ON UPDATE clause. This one is a little less common because it configures what happens when a parent value changes. Obviously, when you are referencing a primary key, the ON UPDATE clause is nearly useless. That's because the primary key value is never supposed to change. If, on the other hand, we have a foreign key referencing a UNIQUE column that is not a primary key, it may change occasionally. So the only times you have to worry about the ON UPDATE clause is with foreign keys referencing UNIQUE columns that are not a primary key, and when you have natural keys that break the rules and actually do change at some point in time. The ON UPDATE clause has the same options as the ON DELETE clause and they all work the same way. Now, the last thing you need to know about foreign keys is that they must match the data type of the column you are referencing. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 15919 Caleb Curry
SQL tutorial 19: ON DELETE SET NULL clause of Foreign Key By Manish Sharma (RebellionRider)
 
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SQL Tutorial 19 : ON DELETE SET NULL foreign key Clause. Links used in the tutorial On delete set null website article [ download SQL script from same link] : http://www.rebellionrider.com/on-delete-set-null.htm Foreign Key Tutorial Video : http://youtu.be/0nbkBI5r3Gw Foreign Key Tutorial Blog : http://www.rebellionrider.com/sql-foreign-key.htm This video is the part of foreign key video In this sql tutorial you will learn the referential clause ON DELETE SET NULL of foreign key. On Delete Set null clause guarantee the relation integrity in foreign key/ Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com
Views: 49260 Manish Sharma
13.52 ON DELETE NO ACTION, SET NULL, CASCADE, SET DEFAULT
 
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Komplette Liste der Videos und zusätzliches Material auf http://datenbankenlernen.de Informatik, Uni Saarland: Bachelor: http://www.cs.uni-saarland.de/index.php?id=52&L=1&source=1352 Master: http://www.cs.uni-saarland.de/index.php?id=132&L=1&source=1352 Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/&source=1352
SQL Server 17 - ON DELETE and ON UPDATE
 
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Now, what happens when you have successfully created a reference, and now you try deleting the parent? This is where the ON DELETE clause comes in. This is essentially how we configure how strict a foreign key is. There are 4 options you can give for an ON DELETE: Standard SQL Server NO ACTION Yes (Default) CASCADE Yes SET NULL Yes SET DEFAULT Yes Now the default is NO ACTION. This means that when you try to delete a parent row, SQL Server is going to throw an error and not let you. Cascade means that if you delete the parent row, any rows that reference that parent will also be deleted. This is pretty dangerous and not often recommended. SET NULL will set the foreign key to be NULL. Now obviously, this is going to require that the foreign key is not labelled NOT NULL. Finally, set DEFAULT will change the reference to the child row to some default value. We have not discussed defaults, but a column can have a default value. For example, we could make a deleted user in our Users table, and set the default for the foreign key to be the deleted user, and when any other users are deleted it will default to the deleted user UserId. In addition to the ON DELETE clause, there is the ON UPDATE clause. This one is a little less common because it configures what happens when a parent value changes. Obviously, when you are referencing a primary key, the ON UPDATE clause is nearly useless. That's because the primary key value is never supposed to change. If, on the other hand, we have a foreign key referencing a UNIQUE column that is not a primary key, it may change occasionally. So the only times you have to worry about the ON UPDATE clause is with foreign keys referencing UNIQUE columns that are not a primary key, and when you have natural keys that break the rules and actually do change at some point in time. The ON UPDATE clause has the same options as the ON DELETE clause and they all work the same way. Now, the last thing you need to know about foreign keys is that they must match the data type of the column you are referencing. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 5856 Caleb Curry
SQL CASCADE, SET DEFAULT, NO ACTION
 
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Jamie King of Neumont University showing the differences between CASCADE, SET DEFAULT, NO ACTION with foreign keys.
Views: 11474 Jamie King
[ Tutorial ] how to make relation table on delete cascade
 
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Tutorial apalagi yang kalian mau tulis di komen..
Views: 83 Intersoft
Primary (PK) and Foreign Key (FK) Relation on Table without Cascade Rules Part 1 | MSSQL Training
 
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Views: 7931 Naresh i Technologies
Tutorial 14- ON DELETE RESTRICT AND CASCADE
 
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Learn About ON DELETE RESTRICT AND ON DELETE CASCADE in PostgreSQL.
Views: 15658 Programming Guru
Oracle Database 12c SQL Certified Associate 1Z0-071 : ON DELETE cascade / ON DELETE set null
 
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http://ytwizard.com/r/PLkVTt http://ytwizard.com/r/PLkVTt Oracle Database 12c SQL Certified Associate 1Z0-071 Become Oracle SQL Certified ( OCA ) / Covers ORACLE university track 100%. All the presentations & scripts are attached
117. ON UPDATE CASCADE in SQL (Hindi)
 
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Views: 5572 Geeky Shows
FOREIGN KEY CONSTAINT IN ORACLE SQL
 
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This is a free video tutorial explaining about foreign key constraint in Oracle SQL database, the video explains about how the foreign key works, how it can be implemented with easy to understand examples. We have also shown practical demonstration on creating the foreign key constraint, and then encountering the part not found, and child record exists kind of integrity constraint.
Views: 788 Kishan Mashru
Oracle SQL Tutorial 20 - How to Create Composite Primary Keys
 
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This video is going to be a tutorial on how to create composite and compound keys. The difference between a composite and compound key is that a composite key can consist of any columns while a compound key has to consist of columns that are all keys themselves. We will be working with a compound key because we are going to be using the an intermediary table that has two foreign keys. The combination of both of the keys have to be unique. First, if we have any other CREATE TABLE commands, we are going to comment those out. We will space out the CREATE TABLE to have each column on a line, then we will add constraints as needed. CREATE TABLE project_users( project_id, user_id ) Now, let's add the data types: CREATE TABLE project_users( project_id NUMBER, user_id NUMBER } Now, what about some column attributes? I'm going to make both of the columns NOT NULL because we always want the rows to have a user and a project: CREATE TABLE project_users( project_id NUMBER NOT NULL, user_id NUMBER NOT NULL } Now, let's add the foreign key constraints. Now, what do we name these? We are going to add a primary key that covers both of these columns, so I'm going to be a sinner and not give these constraints names: CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id), user_id NUMBER NOT NULL REFFERENCES users (user_id) ) Now, the way we have it now is that if we delete a project in the project table, and there are any rows in the project_users table, it will throw an error and prevent deletion. I would prefer for it to also delete any project members. That would make sense because if you delete a project we want it to delete the associate between that project and certain users. The same goes for if we delete a user, we want their association with a certain project to be deleted. To do this, we need to add the ON DELETE command: CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, ) Finally, let's learn how to create a compound or composite key. literally, the only difference is that you put a comma and add the second table inside of the parenthesis. CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ) Now, the combination of project_id and user_id cannot be null, is always unique, and has an index. The only thing we should do now is add a few indexes. We aren't done yet...In the next video we are going to figure out what columns would benefit from indexes and we'll add them to it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 11949 Caleb Curry
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: 850 TechLake
Oracle ||  Referential Integrity Constrants Part-1 by Dinesh
 
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Learn MySQL In Arabic #18 - Constraint - Foreign Key Update, Delete
 
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Learn Foreign Key Options OnUpdate and OnDelete Cascade | Restrict | Set Null | No Action
Views: 11778 Elzero Web School
Oracle SQL Tutorial 21 - How to Create / Drop Indexes
 
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In the last video, we wrote up the SQL to create three tables: CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, CONSTRAINT users_pk PRIMARY KEY (user_id) ); 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 ); CREATE TABLE project_users( project_id NUMBER NOT NULL REFERENCES projects (project_id) ON DELETE CASCADE, user_id NUMBER NOT NULL REFERENCES users (user_id) ON DELETE CASCADE, CONSTRAINT project_users_pk PRIMARY KEY (project_id, user_id) ); I'm going to increase the size of the users table a bit by adding a first and last name column. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR) UNIQUE, first_name VARCHAR2(50 CHAR), last_name VARCHAR2 (50 CHAR), CONSTRAINT users_pk PRIMARY KEY (user_id) ); But before we finish this design, we should consider indexing certain columns. What columns should we index? Well, as a reminder, the columns that are indexed by default are columns with the UNIQUE constraint, and those that are labeled as primary keys. Columns that are not indexed but often should be are those labeled as a foreign key. The column that jumps out the most to me is the creator column of the project table. It's the only foreign key that is not part of some index. Let's fix this by creating our first index. The way we do that is with the CREATE INDEX command. CREATE INDEX projects_creator_ix ON projects (creator) What naming convention are we following for the index? We are naming it by the table name, followed by an underscore, followed by the column, followed by an underscore, followed by an ix (for index). In this situation it does not apply, but if our foreign key column is labeled as UNIQUE, we can add the UNIQUE keyword like this: CREATE UNIQUE INDEX projects_creator_ix ON projects (creator) Now if you want to get rid of an INDEX, you can use this command: DROP INDEX projects_creator_ix Now, if we want to select data from the user table and the project table we can do that much faster. That's because the foreign key and column it references are both indexed and those are the columns we would do the join on. We will discuss how to do joins in a future video. So what are some potential problems with this database design? Overall, it is pretty good. With this design though we need to make sure there is no way for someone to update a user's username. In the next video we are going to discuss why. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 9407 Caleb Curry
DBMS for GATE 2018 - Previous Year Solved Question on Delete, Update, Cascade Options
 
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DBMS for GATE 2018 - Previous Year Solved Question on Delete, Update, Cascade Options How to perform deletion operation on tables having On-delete cascade, On-delete set Null, On-update cascade and On-update set Null constraints DBMS for GATE 2018, UGC NET CSE IT and Bank IT Officer Exam
Oracle - SQL - Foreign Key Constraint
 
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Oracle - SQL - Foreign Key Constraint Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Anadi Sharma, Tutorials Point India Private Limited.
112. ON DELETE Clause in SQL (Hindi)
 
01:02
Please Subscribe Channel Like, Share and Comment Visit : www.geekyshows.com
Views: 4294 Geeky Shows
Primary (PK) and Foreign Key (FK) Relation on Table without Cascade Rules Part 2 | MSSQL Training
 
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Primary (PK) and Foreign Key (FK) Relation on Table without Cascade Rules Part 2 | MSSQL Training | Mr.Sudhakar L 💡For Registration : https://goo.gl/r6kJbB ►Call: +91-8179191999 💡 Visit Our Website: http://nareshit.in/ http://nareshit.com/ 💡 About NareshIT: "Naresh IT is having 14+ years of experience in software training industry and the best Software Training Institute for online training, classroom training, weekend training, corporate training of Hadoop, Salesforce, AWS, DevOps, Spark, Data Science, Python, Tableau, RPA , Java, C#.NET, ASP.NET, Oracle, Testing Tools, Silver light, Linq, SQL Server, Selenium, Android, iPhone, C Language, C++, PHP and Digital Marketing in USA, Hyderabad, Chennai and Vijayawada, Bangalore India which provides online training across all the locations -------------------------- 💡 Our Online Training Features: 🎈 Training with Real-Time Experts 🎈 Industry Specific Scenario’s 🎈 Flexible Timings 🎈 Soft Copy of Material 🎈 Share Videos of each and every session. -------------------------- 💡 Please write back to us at 📧 [email protected]/ 📧 [email protected] or Call us at the USA: ☎+1404-232-9879 or India: ☎ +918179191999 -------------------------- 💡 Check The Below Links ► For Course Reg: https://goo.gl/r6kJbB ► Subscribe to Our Channel: https://goo.gl/q9ozyG ► Circle us on G+: https://plus.google.com/+NareshIT ► Like us on Facebook: https://www.facebook.com/NareshIT ► Follow us on Twitter: https://twitter.com/nareshitek ► Follow us on Linkedin: https://goo.gl/CRBZ5F ► Follow us on Instagram: https://goo.gl/3UXYK3
Views: 5728 Naresh i Technologies
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: 24211 Caleb Curry
Working with Primary & Foreign key Constraint in SQL Server | SQL Server Tutorial
 
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** For Online Training Registration: https://goo.gl/r6kJbB ? Call: +91-8179191999 💡 Visit Our Website for Classroom Training: https://nareshit.in/sql-server-training/ 💡For Online Training: https://nareshit.com/course/sql-server-online-training/ #sqlserver #server #programming #course #Tutorials #Training #Videos -------------------------- -------------------------- 💡 About NareshIT: "Naresh IT is having 14+ years of experience in software training industry and the best Software Training Institute for online training, classroom training, weekend training, corporate training of Hadoop, Salesforce, AWS, DevOps, Spark, Data Science, Python, Tableau, RPA , Java, C#.NET, ASP.NET, Oracle, Testing Tools, Silver light, Linq, SQL Server, Selenium, Android, iPhone, C Language, C++, PHP and Digital Marketing in USA, Hyderabad, Chennai and Vijayawada, Bangalore India which provides online training across all the locations -------------------------- 💡 Our Online Training Features: 🎈 Training with Real-Time Experts 🎈 Industry Specific Scenario’s 🎈 Flexible Timings 🎈 Soft Copy of Material 🎈 Share Videos of each and every session. -------------------------- 💡 Please write back to us at 📧 [email protected]/ 📧 [email protected] or Call us at the USA: ☎+1404-232-9879 or India: ☎ +918179191999 -------------------------- 💡 Check The Below Links ► For Course Reg: https://goo.gl/r6kJbB ► Subscribe to Our Channel: https://goo.gl/q9ozyG ► Circle us on G+: https://plus.google.com/+NareshIT ► Like us on Facebook: https://www.facebook.com/NareshIT ► Follow us on Twitter: https://twitter.com/nareshitek ► Follow us on Linkedin: https://goo.gl/CRBZ5F ► Follow us on Instagram: https://goo.gl/3UXYK3
Views: 67809 Naresh i Technologies
Difference between Delete and Truncate and Drop in Oracle Sql
 
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This is a free tutorial on understanding difference between drop, delete and truncate statements. I have tried to cover most of the major difference between all these three statements and have also shown the same with simple and easy to understand examples. Hope it will be helpful to all. If you want more such videos of exciting and amazing 'difference between' concepts, check out the links below : union and union all : https://youtu.be/n9FqQOd8liY char and varchar2 : https://youtu.be/039qzwjWf4k replace and translate : https://youtu.be/HKYF77BGzOE procedure and function : https://youtu.be/q3LmOenL120 in and exists : https://youtu.be/REX4IjRYlFw rank and dense_rank : https://youtu.be/WGSX998hZ9M %type and %rowtype : https://youtu.be/MlLUFeZ_3eM
Views: 1885 Kishan Mashru
SelectTec | Aula Nº 32 | Continuação Cascade/Restrict - Oracle SQL Developer
 
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ALTER TABLE table_name ADD CONSTRAINT constraint_name FOREIGN KEY (column1, column2, ... column_n) REFERENCES parent_table (column1, column2, ... column_n) ON DELETE CASCADE;
Views: 1072 SelectTec
SQL in Oracle 11g Tutorial #7: Alter table( Add, Delete , Enable and Disable Primary Key)
 
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SQL in Oracle 11g Tutorial #7: Alter table( Add, Delete , Enable and Disable Primary Key). This video will explain you the following: 1. How to Add the Primary Key 2. How to delete the primary Key 3. How to Enable the Primary Key 4. How to disable the primary key Thanks for Watching my Channel “Learn TechToTech”. Please subscribe my channel for getting first updates after uploading video.Social Media pages of Channel are: 1. My Website : www.learnfromrakesh.com 2. My Twitter: https://twitter.com/LearnTechtotech 3. Facebook Page: https://www.facebook.com/LearnTechToTech 4. Blogger : https://learntechtotech.blogspot.in/ 5. Google+ : https://learntechtotech.blogspot.in/ 6. Pinterest : https://in.pinterest.com/LearnTechToTech/ 7. LinkedIn: https://www.linkedin.com/in/Learntechtotech/ Playlist of Different Technology: 1. Operating System : https://goo.gl/q6SfrW 2. Python Programming Language : https://goo.gl/L8b5dc 3. C Language : https://goo.gl/SwvDu9 4. C language for Placement: https://goo.gl/AaQBa4 5. Java: https://goo.gl/M8F2uy 6. MySql : https://goo.gl/vdJbHQ 7. Android Mobile Application Development: https://goo.gl/M6woaT 8. Kotlin Programming Language : https://goo.gl/GXE5cd 9. Go Programming: https://goo.gl/Ua3xYW 10. Internet of Things(IoT): https://goo.gl/f2afkY 11. Oracle 11g : https://goo.gl/zds8r2 12. C++ : https://goo.gl/C1psMT
Views: 500 Learn TechToTech
On Delete Cascade - SQLServer
 
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http://xtutorialsplus.blogspot.com/ Se muestra con un ejemplo el uso de On Delete Cascade en SQL Server 2008.
Views: 14982 Aneudy Abreu
SQL tutorials 17: SQL Primary Key constraint,  Drop primary Key
 
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Blog link: http://www.rebellionrider.com/sql-primary-key.htm SQL tutorial on Primary key / SQL Primary key, In this tutorial you will learn about simple primary key, composute primary key, how to drop primary key. defining primary key using create table and alter table along with many other things. Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com So Primary Key There are two types of Primary keys First is Simple primary Key: Primary key which Involves only one column and Second is Composite Primary Key: Primary Key which involves more than one column. We will start with Simple primary key. You can create Primary key either with Create Table statement of by using Alter table Statement. Let's define simple primary key using create table statements. With create table statement we can either define primary key at column level or at table level. We will start with defining Primary key at column level using create table statement. You just have to put keyword Primary key after data type and size of column while defining a column of a table. Here oracle server will create a primary key on product id with default constraint name which will be slightly difficult to understand. You can give your own name to your constraint which is also a good practice.
Views: 102225 Manish Sharma
SQL tutorials 18: SQL Foreign Key Constraint By Manish Sharma
 
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SQL Tutorial 18: SQL foreign key constraint. Topic covered in this tutorial 1. Defining SQL foreign key using create table at column level 2. Defining SQL foreign key using create table at table level 1. Defining SQL foreign key using Alter Table statement Links Website article: http://www.rebellionrider.com/sql-foreign-key.htm Primary key tutorial: http://www.rebellionrider.com/sql-foreign-key.htm Create Table Tutorial: http://www.rebellionrider.com/sql-create-table.html Tool used in this tutorial is SQL Developer. This tutorial series is part of SQL expert exam certification training. if you are preparing for SQL certification you can use my tutorials. This SQL Tutorial is a part of free training. Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=j7eYO7 Contacts E-Mail [email protected] Twitter https://twitter.com/rebellionrider Instagram http://instagram.com/rebellionrider Facebook. https://www.facebook.com/imthebhardwaj Linkedin. http://in.linkedin.com/in/mannbhardwaj/ Thanks for linking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com Foreign key is an Input/output data constraint which is also known as referential integrity constraint. Foreign key represent a link or say a relationship between columns of tables. Similar to primary key constraint Foreign Key constraint is also of two types. Simple Foreign key constraint and Composite Foreign key constraint. Constraint which involves only one column in foreign key in child table and one column in reference key in parent table is called Simple Foreign Key. While the constraint which involves more than one column in foreign key in child table and more than one column in reference key in the parent table is called Composite Foreign Key.
Views: 103790 Manish Sharma
Database - Foreign Keys Part 2 - Adding and Deleting Data
 
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This is part 2 of the video's on foreign keys. It shows how data must be added or deleted when considering foreign key constraints in a database.
SQL Delete Statement with Example on Oracle 11g Database
 
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SQL Lecturers for Beginners in Hindi and English SQL Delete Statement with Example on Oracle 11g Database
Simulasi On Delete Cascade Menyebabkan Deadlock di Oracle
 
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Kali ini kita akan coba melakukan Simulasi On Delete Cascade Menyebabkan Deadlock di Oracle. Artikel Ini kami harap dapat membantu kita semua dalam membuat foreign key untuk lebih berhati-hati saat menambahkan on delete cascade. Artikel ini masih berhubungan dengan artikel Simulasi Deadlock pada Database Oracle. url: https://wijaksana.com/index.php/2018/01/22/simulasi-delete-cascade-menyebabkan-deadlock-di-oracle/
Views: 13 Yulianto Wijaksana
MySQL Cascade on Delete & Cascade on Update Urdu/Hindi
 
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In this video, you will learn how to set CASCADE ON DELETE and CASCADE ON UPDATE. In Exampp version 3.2.2. In this version of Exampp, they have moved the CASCADE option from PHPMyAdmin designer to somewhere else and you will learn how to set CASCADE on Update and on Delete in this video. Buy my courses online: https://proetutor.com/courses Want to get our cutting edge web development services? Feel free to contact us Assad Ullah Chaudhry Mobile/WhatsApp: +92 332 4737443 Mobile/WhatsApp: +92 321 7214816 DO NOT CONTACT ON MY BUSINESS NUMBERS FOR NON BUSINESS QUERIES.
Views: 653 AssadUllahCh
How to create Foreign Key Constraint with ON DELETE CASCADE in SQL Server - SQL Server Tutorial 80
 
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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 be deleted from Parent Table ( Foreign Key Constraint Table) as well. Link to scripts used in SQL Server / TSQL Tutorial Video http://www.techbrothersit.com/2016/04/how-to-create-foreign-key-constraint_29.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: 3418 TechBrothersIT
Merge Statement in Oracle SQL with Example (UPDATE/DELETE or INSERT)
 
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This video demonstrates how to write a Merge Statement in oracle sql, how it is useful in doing a conditional update or delete or both of them when the condition between the target table and source table is evaluated to true, and how we can insert the record into the target table when condition is evaluated to false. The video also shows the use of UPDATE, DELETE and INSERT with Merge, and also the various possible ways to use a Merge statement!!!
Views: 9633 Kishan Mashru
Cascading referential integrity constraint - Part 5
 
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In this video, we will learn about Cascading referential integrity constraint Text version of the video http://csharp-video-tutorials.blogspot.com/2012/08/cascading-referential-integrity.html Slides http://csharp-video-tutorials.blogspot.com/2013/08/part-5-cascading-referential-integrity.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html 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
Views: 492676 kudvenkat
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.
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: 991 TechBrothersIT
Oracle SQL Tutorial 14 - Column-Level and Table-Level Constraints
 
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In the previous video we talked about adding constraints at the column-level. We made it nice and simple by only requiring a few keywords, but the problem we were having is that we could not assign a name to the constraint, which many people like to do so we can reference easily if we need to at a later time. To do this, it requires a little bit more typing, but it will give us extra flexibility and many consider it to be the higher quality approach to adding constraints. Let's go though a simple example. Let's say we have a users table with a user_id column that we want to make a primary key. We will create the table like this: CREATE TABLE( user_ id NUMBER PRIMARY KEY ) Instead of adding the PRIMARY KEY keywords after the data type, we add: CONSTRAINT user_pk PRIMARY KEY Now, we have assigned the name user_pk to this constraint. You can do the same with other constraints, such as UNIQUE. The syntax would be CONSTRAINT username_un UNIQUE. The other way to create constraints requires to put all of our constraints at the bottom of our table creation rather than inline with the column. This type of constraint is known as a table-level constraints. To make a column a primary key using table-level constraints, we add it to the CREATE TABLE command as if it is another row and use the CONSTRAINT keyword to tell Oracle that what is coming is a constraint, not a column in our table. CREATE TABLE users( user_id NUMBER, username VARCHAR2(50 CHAR), CONSTRAINT username_un UNIQUE (username), CONSTRAINT users_pk PRIMARY KEY (user_id) ) The primary differences here is that you have to put the column you are talking about in parenthesis after the PRIMARY KEY keyword. That's because it's at the end of the table and you need a way to tell it what column you are talking about. The option of putting it at the end of the table has the added benefit in this situation because if we needed to have a primary key that is the combination of multiple columns, we can do that by just adding the other column in the PRIMARY KEY parenthesis right after a comma. In summary, there are three ways to make constraints. The first is at the column level, unnamed. The second is at the column level, named. The third is at the table level, also named. In the next video we are going to create a named constraint in Oracle SQL Developer, so stay tuned and be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 16556 Caleb Curry
Oracle SQL Tutorial 12 - Intro to Constraints
 
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As I believe I've mentioned in an earlier video, a constraint is basically a rule we can put in our database that prevents someone from putting the wrong data in. It protects our relationships and data integrity. Because the goal of these constraints are to protect our data integrity, you may hear them called integrity constraints. There are many integrity constraints we are going to talk about: NOT NULL UNIQUE PRIMARY KEY FOREIGN KRY CHECK There is also the DEFAULT attribute. These are all keywords we can add to our columns that will change the way the database works with our data and also prevents incorrect data. NOT NULL is a constraint you can put on a column that prevents nulls. A null is the absence of a value. When we say null, we are saying that every single row has to have a value for this column. UNIQUE is a constraint that makes every row have a unique value for this column. Now note, this does not require values to be put it, and it will allow multiple rows to be null. Next, we are going to talk about primary keys. What qualifies a column as a candidate key? First, not a single row should have a null for that column. Second, every row must be unique. The primary key constraint is essentially a combination of the NOT NULL constraint and the UNIQUE constraint. The foreign key constraint sets the requirement that any value in this column for any row must match a row in another column. Check constraints allow us to be more strict with what data is allowed in our database. NOT NULL and UNIQUE give some level of restriction, but what if we want something more specific? For example, what if we only want values between 0 and 100? That is where check constraints come in. When using check constraints, you give a boolean expression. A boolean expression is something that can be evaluated to true or false. It will only insert the row if the value you try to put into the row makes the expression evaluate to true. So if you put in a value too great or small, the expression will be false and the data is not allowed to be entered. The default constraint is a value you can give a column, and if for any reason when the row is created in the table a value is not provided, the default value will be given. So for example, we could have a bank account table where the balance defaults to 0. How do you actually implement these constraints when you are creating a table? In the next video we are going to be adding these to our users table. Please be sure to subscribe! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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: 22721 Caleb Curry
How to Delete Table in sql using oracle 10g or sql
 
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This video gives information about How to Delete Table in sql using oracleXE 10g
Views: 3284 AvilTwo Beginer