Обсуждение: INTERVAL in a function

I have a simple function which I use to set up a users' expiry date. If
a field in a table contains an interval then
this function returns a timestamp some time in the future (usually two
weeks), null otherwise. I can't pass the
interval from the table into a variable properly within the function.
Any ideas?

CREATE OR REPLACE FUNCTION getUnitTimeLength(int) RETURNS timestamp AS '

  DECLARE
    grpID ALIAS FOR $1;
    intval INTERVAL;
    exptime TIMESTAMP;
  BEGIN
    SELECT INTO intval unitTimeLength::INTERVAL FROM customer.groups WHERE groupsID = grpID;
    IF intval IS NULL THEN
      RETURN NULL;
    ELSE
      SELECT INTO exptime current_timestamp + INTERVAL ''intval'';
      RETURN exptime;
    END IF;
  END;
' LANGUAGE 'plpgsql';


SELECT getUnitTimeLength(55);

ERROR:  invalid input syntax for type interval: "intval"
CONTEXT:  PL/pgSQL function "getunittimelength" line 11 at select into variables


However if I change the else clause to this:
    ELSE
      SELECT INTO exptime current_timestamp;
      RETURN exptime;
    END IF;
it works:
----------------------------
 2004-11-08 16:14:40.273597
(1 row)


Thanks
Ron

On Mon, Nov 08, 2004 at 04:15:34PM -0800, Ron St-Pierre wrote:

> SELECT INTO exptime current_timestamp + INTERVAL ''intval'';

You're using the literal value 'intval' instead of its value, thus
the syntax error.  You can simplify the statement to this:

exptime := current_timestamp + intval;

But I think the entire function can be shortened to:

CREATE OR REPLACE FUNCTION getUnitTimeLength(int) RETURNS TIMESTAMP AS '
SELECT CURRENT_TIMESTAMP::timestamp + unitTimeLength
FROM customer.groups
WHERE groupsID = $1
' LANGUAGE sql;

You don't need to check for NULL because the result of the addition
will already be NULL if either operand is NULL.  Casting CURRENT_TIMESTAMP
is necessary to avoid a "return type mismatch" error.

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/

Michael Fuhr wrote:

>On Mon, Nov 08, 2004 at 04:15:34PM -0800, Ron St-Pierre wrote:
>
>
>
>>SELECT INTO exptime current_timestamp + INTERVAL ''intval'';
>>
>>
>
>You're using the literal value 'intval' instead of its value, thus
>the syntax error.
>
Of course, I should have caught that.

>You can simplify the statement to this:
>
>exptime := current_timestamp + intval;
>
>But I think the entire function can be shortened to:
>
>CREATE OR REPLACE FUNCTION getUnitTimeLength(int) RETURNS TIMESTAMP AS '
>SELECT CURRENT_TIMESTAMP::timestamp + unitTimeLength
>FROM customer.groups
>WHERE groupsID = $1
>' LANGUAGE sql;
>
>You don't need to check for NULL because the result of the addition
>will already be NULL if either operand is NULL.  Casting CURRENT_TIMESTAMP
>is necessary to avoid a "return type mismatch" error.
>
>
>
Perfect.
 Thanks Michael!