SELECT column WHERE (type = 'S' OR type = 'B') but perform different actions depending on whether type = 'S' or 'B' - Mailing list pgsql-admin

Hi all, this is my table...

<http://postgresql.nabble.com/file/n5855422/screenshot.jpg>

I only want to select **one** "time" row, **either** WHERE "time_type" =
'Start' OR "time_type" = 'Break', **but only one**, the one that is at the
bottom row (descending) (ORDER BY "fn_serial" DESC LIMIT 1).

Im successfully doing it by using this Trigger Function...

*    CREATE OR REPLACE FUNCTION timediff()
      RETURNS trigger AS
    $BODY$
    DECLARE
    prevtime character varying;

    BEGIN
    SELECT t.time FROM table_ebscb_spa_log04 t WHERE t.fn_name = NEW.fn_name
AND (t.time_type = 'Start' OR time_type = 'Break') ORDER BY t.fn_serial DESC
LIMIT 1 INTO prevtime;
      IF NOT FOUND THEN
        RAISE EXCEPTION USING MESSAGE = 'NOT FOUNDED';
      ELSE
        NEW.time_elapse := prevtime
      END IF;
    return NEW;
    END
    $BODY$
      LANGUAGE plpgsql VOLATILE
      COST 100;
    ALTER FUNCTION timediff()
      OWNER TO postgres;*

But in my script I would like to perform different actions depending on
whether "fn_type" = 'Start' OR "fn_type = 'Break', I mean where "prevtime"
variable came from, eg:

*    IF "prevtime" came from "fn_type" = 'Start' THEN
    RAISE EXCEPTION USING MESSAGE = 'PREVTIME CAME FROM START';
    ELSIF "prevtime" came from "fn_type" = 'BREAK' THEN
    RAISE EXCEPTION USING MESSAGE = 'PREVTIME CAME FROM BREAK';*

I can guess a way to do that, but its redundant, So I would like to ask
suggestions from good PostgreSQL fellow programmers.

Thanks Advanced.



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