如何在ORACLE PL / SQL中创建触发器以不允许双精度值？

Question

I've a table named cliente with columns: COD_CLIENTE, CPF_CLIENTE and NAME_CLIENT.

How to make a TRIGGER in PL SQL to not allow insert or update double CPF_CLIENTE's values?

I've tryied:

CREATE OR REPLACE TRIGGER TG_CPF
  BEFORE INSERT ON CLIENTE
  FOR EACH ROW
DECLARE 
  CONDITION_CHECK NUMBER;
BEGIN
  SELECT COUNT(CPF_CLIENTE) INTO CONDITION_CHECK FROM CLIENTE WHERE CPF_CLIENTE = :new.CPF_CLIENTE;
  IF CONDITION_CHECK > 0 THEN
    RAISE_APPLICATION_ERROR (-20000, ' CPF is Already in DB.');
  END IF;
END;
/

But i got:

ORA-20000:  CPF is Already in DB.
ORA-06512: at "USER.TG_CPF", line 6
ORA-04088: error during execution of trigger 'USER.TG_CPF'

Why I'm getting ORA-06512 and ORA-0488 errors?

The trigger does what i need. Don't insert/update the value if already exits, but i'm getting these 2 errors.

How to fix it, please?

Thank you!

Answer 1

You cannot have a trigger on a table, and read data from that same table in the trigger body, when it's a row level trigger.

Instead, you need to use a unique constraint.