SQL Constraint

FOREIGN KEY WITH Cascade DELETE

It indicates that when the parent table’s entry is deleted, the matching record in the child table is also deleted

It can be used in two ways

1. CREATE

    CREATE TABLE [TABLE NAME] (
    ~~
    CONSTRAINT [CONSTRAINT NAME] FOREIGN KEY ([KEY NAME])
    REFERENCES [TABLE NAME] ([COLUMN NAME])
    ON DELETE CASCADE;
   

2. ALTER

  ALTER TABLE [CHILD TABLE NAME]
  ADD CONSTRAINT [fk_name]
  FOREIGN KEY ([CHILD COLUMN])
  REFERENCE TABLE [PARENT TABLE] (PARENT COLUMN)
  ON DELETE CASCADE;

1. SEQUENCE

   CREATE SEQUENCE [SEQUENCE NAME] START WITH [STARTING VALUE] INCREMENT BY [INCREMENT VALUE]
   

Ref:

https://www.techonthenet.com/sql_server/foreign_keys/foreign_delete.php#:~:text=What%20is%20a%20foreign%20key,cascade%20delete%20in%20SQL%20Server.