SELECT a.account_no,      (CASE          WHEN e.reading_month IS NULL then ""          WHEN e.reading_month IS NOT NULL then STR_TO_DATE(CONCAT(e.reading_month," ",e.reading_year), "%m %Y")          end) as reading_date,       (CASE          WHEN e.reading_month IS NULL then "" else e.reading        end) as reading  FROM swws_users as a, water_reading as e  WHERE e.account_no = a.account_no OR e.account_no is NULL AND      (CASE          WHEN e.reading_month IS NULL then ""          WHEN e.reading_month IS NOT NULL then STR_TO_DATE(CONCAT(e.reading_month," ",e.reading_year), "%m %Y")=             (SELECT MAX(STR_TO_DATE(CONCAT(j.reading_month," ",j.reading_year), "%m %Y"))               FROM water_reading as j,swws_users as k               WHERE j.account_no=e.account_no)      end)  GROUP BY a.account_no 

it will still output

 |account_no | reading_date | reading |  ======================================   |040000238  |  2017-12-00  | 2230    | |13112546   |  2017-12-00  |  738    |

it will only fetch the one with the data in the second table

while the output i want is

 |account_no | reading_date | reading |  ======================================   |040000238  |  2017-12-00  | 2230    | |13112546   |  2017-12-00  |  738    | |00023134   |     NULL     | NULL    | |131324555  |     NULL     | NULL    | |00031-FREE |     NULL     | NULL    |