Question

I found a weird problem with MySQL select statement having “IN” in where clause:

I am trying this query:

SELECT ads.* 
  FROM advertisement_urls ads 
 WHERE ad_pool_id = 5 
   AND status = 1 
   AND ads.id = 23 
   AND 3 NOT IN (hide_from_publishers) 
ORDER BY rank desc

In above SQL hide_from_publishers is a column of advertisement_urls table, with values as comma separated integers, e.g. 4,2 or 2,7,3 etc.

As a result, if hide_from_publishers contains same above two values, it should return only record for “4,2” but it returns both records

Now, if I change the value of hide_for_columns for second set to 3,2,7 and run the query again, it will return single record which is correct output.

Instead of hide_from_publishers if I use direct values there, i.e. (2,7,3) it does recognize and returns single record.

Any thoughts about this strange problem or am I doing something wrong?

Answer 1

You need to treat the comma-delimited hide_from_publishers column as a string. You can use the LOCATE function to determine if your value exists in the string.

Note that I’ve added leading and trailing commas to both strings so that a search for “3” doesn’t accidentally match “13”.

select ads.* 
    from advertisement_urls ads 
    where ad_pool_id = 5 
        and status = 1 
        and ads.id = 23 
        and locate(',3,', ','+hide_from_publishers+',') = 0
    order by rank desc