referential actions with trigger

Question

I have this task to emulate a referential action with a trigger. The task itself is: Give an example of how to use a trigger to emulate a referential action.

I know hot to use triggers and referential actions but combined I just don't really get it, and the question itself.

By "referential action" do they mean "foreign key constraint"? — Tony Andrews, Jun 14 '13 at 10:24
they mean one of these `ON DELETE CASCADE` , `... SET NULL` , etc... for `foreign keys` — Milkncookiez, Jun 14 '13 at 10:47
OK so for example `ON DELETE CASCADE` simply means: when a row is deleted from this table, also delete any dependent rows from child tables. — Tony Andrews, Jun 14 '13 at 11:11

score 1 · Accepted Answer · answered Jun 14 '13 at 11:28

1

Given that the least objectionable of the options you listed is to do a cascading delete when a parent row is removed

CREATE OR REPLACE TRIGGER trigger_name
  AFTER DELETE ON parent_table
  FOR EACH ROW
BEGIN
  DELETE FROM child_table
   WHERE parent_id = :old.parent_id;

  <<repeat for each child table>>
END;

answered Jun 14 '13 at 11:28

Justin Cave

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So I basically had to simulate the referential action through basic logical statements. That is what I needed to understand. Thank you! – Milkncookiez Jun 14 '13 at 13:41

referential actions with trigger

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