>
> I have a table with a column named SwErr (Switch Error) with int
values
> date with datetime values and SwID with char(3)
> I am trying to get a subset back where the folowing is true
>
> select the avg(SwErr) for the last 30 days where SwId = 'XX1'
> Select the value of todays value of SwErr where SwId = 'XX1'
> if todays value of SwErr is greater than 4 times the SwErr Average
return in
> the value
>
Looks like you could use a plpgsql function, something like (untested)
CREATE OR REPLACE FUNCTION
get_dated_SwErr(CHAR) RETURNS INTEGER AS '
DECLAREthisSwID ALIAS FOR $1;todaysSwErr INT;avgSwErr INT;avg4SwErr INT;dateLimit TIMESTAMP;
BEGIN
SELECT INTO dateLimit current_date - ''30 days''::interval ;
SELECT INTO todaysSwErr SwErr FROM <SwTable>WHERE SwID = thisSwID AND SwDate = current_date ;
SELECT INTO avgSwErr AVG(SwErr)::int FROM <SwTable>WHERE SwID = thisSwID AND SwDate BETWEEN current_date AND dateLimit
;
avg4SwErr := avgSwErr * 4 ;
IF todaysSwErr > avg4SwErr THENRETURN todaysSwErr;
ELSERETURN avgSwErr;
END IF;
END;
' LANGUAGE 'plpgsql' ;
then
SELECT SwID, get_dated_SwErr(SwID) FROM <SwTable>WHERE SwID = 'XX1' AND SwDate = current_date ;
should bring up the result.
Regards, Christoph
