Question

I have a table with a lastaccess date in a unix format. I would like to query all the records in the table where the lastaccess date is greater than 180 days.

This is my current query

SELECT  id, auth, username, IF(DATEDIFF(NOW(), FROM_UNIXTIME(lastaccess))>=180,'Y','N') As NotAccessedIn6Months
FROM  mdl_user 
WHERE auth = 'manual'

I need to be able to use the NotAccessedIn6Months result to filter the resultset, like

SELECT  id, auth, username, IF(DATEDIFF(NOW(), FROM_UNIXTIME(lastaccess))>=180,'Y','N') As NotAccessedIn6Months
FROM  mdl_user 
WHERE auth = 'manual' AND NotAccessedIn6Months = 'Y'

but the latter format is illegal.

Thank you.

Answer 1

You have two options: either use HAVING instead of WHERE, like this:

SELECT id, auth, username, 
       IF(DATEDIFF(NOW(), FROM_UNIXTIME(lastaccess))>=180,'Y','N') As NotAccessedIn6Months
  FROM mdl_user 
 WHERE auth = 'manual' 
HAVING NotAccessedIn6Months = 'Y'

… or just move this condition into WHERE (as you won’t show ‘N’ values at all in this particular query), like that:

SELECT id, auth, username 
  FROM mdl_user 
 WHERE auth = 'manual' 
   AND DATEDIFF(NOW(), FROM_UNIXTIME(lastaccess)) >= 180