Re: FOR EACH STATEMENT trigger ?

Hello

it isn't bug. PostgreSQL doesn't support NEW and OLD tables like MSSQL
does for statement triggers.

Regards

Pavel Stehule

2011/5/6 Frédéric BROUARD <brouardf(at)club-internet(dot)fr>:
> Hi there
>
> I am trying to get an example of SET BASED trigger logic with FOR EACH
> STATEMENT, but I cannot find any example involving the pseudo table NEW (or
> OLD) in the trigger function SQL statement.
>
> Let me give you a real life example.
>
> Suppose we have the above table :
>
> CREATE TABLE T_PRODUIT_DISPO_PDD
> (PRD_ID         INT         NOT NULL,
>  PDD_BEGIN      DATE        NOT NULL,
>  PDD_END        DATE,
>  PDD_QUANTITY   FLOAT       NOT NULL);
>
> We want to never have more thant one PDD_END = NULL for the same PRD_ID.
>
> The assertion we can do is :
>
> ALTER TABLE T_PRODUIT_DISPO_PDD
>   ADD CONSTRAINT CK_PDD_PRD_FIN_UNIQUENULL
>      CHECK (NOT EXISTS(SELECT 0
>                        FROM   T_PRODUIT_DISPO_PDD
>                        WHERE  PDD_FIN IS NULL
>                        GROUP  BY PRD_ID
>                        HAVING COUNT(*) > 1))
>
> Which is not supported by PG
>
> So I wuld like to do this with a FOR EACH STATEMENT trigger and not by a FOR
> EACH ROW.
>
> Here is the code I try :
>
> CREATE OR REPLACE FUNCTION F_UNIQUE_NULL_PRD_END() RETURNS trigger AS
> $code$
> DECLARE n_rows integer;
> BEGIN
> SELECT COUNT(*) INTO n_rows
> WHERE EXISTS(SELECT 0
>             FROM   T_PRODUIT_DISPO_PDD
>             WHERE  PRD_ID IN(SELECT NEW.PRD_ID
>                              FROM   NEW) AS T
>               AND  PDD_END IS NULL
>             GROUP  BY PRD_ID
>             HAVING COUNT(*) > 1);
> IF ( n_rows IS NOT NULL )
>   THEN RAISE EXCEPTION 'Violation de la contrainte d''unicité sur le couple
> de colonne PRD_ID + PDD_FIN';
>   ROLLBACK TRANSACTION;
> END IF;
> RETURN NULL;
> END
> $code$ LANGUAGE 'plpgsql' VOLATILE
>
> Which produce an error !
>
> Of course I can do that with a FOR EACH STATEMENT like this one :
>
> CREATE OR REPLACE FUNCTION F_UNIQUE_NULL_PRD_FIN() RETURNS trigger AS
> $code$
> DECLARE n_rows integer;
> BEGIN
> SELECT 1 INTO n_rows
> WHERE EXISTS(SELECT 0
>             FROM   T_PRODUIT_DISPO_PDD
>             WHERE  PRD_ID = NEW.PRD_ID
>               AND  PDD_FIN IS NULL
>             GROUP  BY PRD_ID
>             HAVING COUNT(*) > 1);
> IF ( n_rows IS NOT NULL )
>   THEN RAISE EXCEPTION 'Violation de la contrainte d''unicité sur le couple
> de colonne PRD_ID + PDD_FIN';
>   ROLLBACK TRANSACTION;
> END IF;
> RETURN NULL;
> END
> $code$ LANGUAGE 'plpgsql' VOLATILE
>
> CREATE TRIGGER E_IU_PRD
>   AFTER INSERT OR UPDATE
>   ON T_PRODUIT_DISPO_PDD
>   FOR EACH ROW EXECUTE PROCEDURE F_UNIQUE_NULL_PRD_FIN();
>
>
> But it is absolutly not that I Want !!!!
>
> Thanks
>
>
> --
> Frédéric BROUARD - expert SGBDR et SQL - MVP SQL Server - 06 11 86 40 66
> Le site sur le langage SQL et les SGBDR  :  http://sqlpro.developpez.com
> Enseignant Arts & Métiers PACA, ISEN Toulon et CESI/EXIA Aix en Provence
> Audit, conseil, expertise, formation, modélisation, tuning, optimisation
> *********************** http://www.sqlspot.com *************************
>
>
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