How do you use cascading delete?

How do you use cascading delete?

Edit table and columns specification by clicking … as shown in the below image.

1. Select the parent table and the primary key column in the parent table.
2. In the INSERT and UPDATE specifications, select Cascade for the delete rule.
3. Click on Close and save the table in the designer.

What is on Cascade delete?

Use the ON DELETE CASCADE option to specify whether you want rows deleted in a child table when corresponding rows are deleted in the parent table. If you do not specify cascading deletes, the default behavior of the database server prevents you from deleting data in a table if other tables reference it.

Why do we use on delete cascade in SQL?

ON DELETE CASCADE constraint is used in MySQL to delete the rows from the child table automatically, when the rows from the parent table are deleted. For example when a student registers in an online learning platform, then all the details of the student are recorded with their unique number/id.

What is on delete Set null?

A foreign key with “set null on delete” means that if a record in the parent table is deleted, then the corresponding records in the child table will have the foreign key fields set to NULL. A foreign key with set null on delete can be created using either a CREATE TABLE statement or an ALTER TABLE statement.

When to use Cascade delete in Microsoft Excel?

The first option is only valid for optional relationships where the foreign key property (and the database column to which it is mapped) must be nullable. The second option is valid for any kind of relationship and is known as “cascade delete”.

Which is the referencing table in PostgreSQL delete Cascade?

PostgreSQL DELETE CASCADE foreign key The table containing the foreign key is called the referencing table or child table. The parent table refers to the table to which the foreign key is related. A foreign key in the PostgreSQL child table is a reference to the primary key in the parent table.

When to delete cascade in SQL Server foreign key?

DELETE CASCADE: When we create a foreign key using this option, it deletes the referencing rows in the child table when the referenced row is deleted in the parent table which has a primary key.

How to control the timing of Cascade delete?

The exact timing of when cascading behaviors happen to tracked entities can be controlled using ChangeTracker.CascadeDeleteTiming and ChangeTracker.DeleteOrphansTiming. See Changing Foreign Keys and Navigations for more information.