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in SQL by (20.3k points)

I have a foreign key constraint in my table, I want to add ON DELETE CASCADE to it.

I have tried this:

alter table child_table_name

  modify constraint fk_name

  foreign key (child_column_name)

  references parent_table_name (parent_column_name) on delete cascade;

It doesn't work.

EDIT:

Foreign key already exists, there are data in the foreign key columns.

The error message I get after executing the statement:

ORA-02275: such a referential constraint already exists in the table

1 Answer

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by (40.7k points)

You can not add ON DELETE CASCADE to an already existing constraint. You should drop and re-create the constraint. 

Have a look at this documentation  shows that the MODIFY CONSTRAINT clause can only modify the state of a constraint  (i-e: ENABLED/DISABLED...).

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