How to Alter Constraint

Question

SQL How to Alter Constraint

Below is 1 of my constraint

CONSTRAINT ACTIVEPROG_FKEY1 FOREIGN KEY(ActiveProgCode) REFERENCES PROGRAM(ActiveProgCode),

I want to add in

ON DELETE CASCADE

to the constraint above.

How do i alter that existing constraint ACTIVEPROG_FKEY1 and add

ON DELETE CASCADE

to constraint ACTIVEPROG_FKEY1

Consider ACTIVEPROG_FKEY1 is at Table ACTIVEPROG

Accepted Answer

You can not alter constraints ever but you can drop them and then recreate.

Have look on this

ALTER TABLE your_table DROP CONSTRAINT ACTIVEPROG_FKEY1;

and then recreate it with ON DELETE CASCADE like this

ALTER TABLE your_table
add CONSTRAINT ACTIVEPROG_FKEY1 FOREIGN KEY(ActiveProgCode) REFERENCES PROGRAM(ActiveProgCode)
    ON DELETE CASCADE;

hope this help

Answer 2

No. We cannot alter the constraint, only thing we can do is drop and recreate it

ALTER TABLE [TABLENAME] DROP CONSTRAINT [CONSTRAINTNAME]

Foreign Key Constraint

Alter Table Table1 Add Constraint [CONSTRAINTNAME] Foreign Key (Column) References Table2 (Column) On Update Cascade On Delete Cascade

Primary Key constraint

Alter Table Table add constraint [Primary Key] Primary key(Column1,Column2,.....)

2 Answers