MySQL Question: IS it possible to set up IF statements inside the SELECT statement in a Stored Proc

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I am using MySql with Workbench

I have not been able to use the MAX(C.LastContact) agregate in the WHERE clause which is needed to get the correct results. I am thinking another way to do this might be to set up IF statements in the SELECT statement based on the value of a parameter passed into the Stored Procedure. Is this possible. I have not been able to get it to work. I am using Dynamic SQL. Below is a portion of the code:

SET SelectStmt =

"SELECT COUNT(distinct(C.LocationID))AS 'Total Locations',

IF Parameter1 = 'all'
THEN do this

IF((select max(TIMESTAMPDIFF(minute, C1.LastContact, NOW() ))
from computers c1 where c1.locationid = c.locationid) >= @TimeToFail,'Fail','OK')
AS 'Status',

IF Parameter1 = 'fail'
THEN do this

IF Parameter1 = 'ok'
THEN do this

FROM
Computers AS C ";

SET WhereClause = CONCAT(WhereClause, " IFNULL(TIMESTAMPDIFF(minute, C.LastContact, NOW()),0) ",
'>=',@TimeToFail);

SET GroupBy = " GROUP BY C.LocationID ";

Posted 26-Dec-12 3:46am

SQL Ed

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Hasham Ahmad · Answer 1 · 2012-12-26T05:26:00

you can use CASE WHEN THEN statement to achieve this functionality. an example for this is as follows.

SQL

SET SelectStmt =


"SELECT COUNT(distinct(C.LocationID))AS 'Total Locations',

CASE

WHEN Parameter1 = 'all'
THEN --do this


--IF((select max(TIMESTAMPDIFF(minute, C1.LastContact, NOW() ))
--from computers c1 where c1.locationid = c.locationid) >= @TimeToFail,'Fail','OK')
--AS 'Status',


WHEN Parameter1 = 'fail'
THEN --do this


WHEN Parameter1 = 'ok'
THEN --do this

END AS 'Status'

FROM
Computers AS C ";

SET WhereClause = CONCAT(WhereClause, " IFNULL(TIMESTAMPDIFF(minute, C.LastContact, NOW()),0) ",
'>=',@TimeToFail);

SET GroupBy = " GROUP BY C.LocationID ";

please check and reply if it works.