> SELECT NULLIF('2015-11-19 15:08:22', 0);
+----------------------------------+
| NULLIF('2015-11-19 15:08:22', 0) |
+----------------------------------+
| 2015-11-19 15:08:22 |
+----------------------------------+
1 row in set, 1 warning (0.00 sec)
> SHOW WARNINGS;
+---------+------+---------------------------------------------------------+
| Level | Code | Message |
+---------+------+---------------------------------------------------------+
| Warning | 1292 | Truncated incorrect DOUBLE value: '2015-11-19 15:08:22' |
+---------+------+---------------------------------------------------------+
1 row in set (0.00 sec)
> SELECT NULLIF('2015-11-19 15:08:22', '0000-00-00 00:00:00');
+------------------------------------------------------+
| NULLIF('2015-11-19 15:08:22', '0000-00-00 00:00:00') |
+------------------------------------------------------+
| 2015-11-19 15:08:22 |
+------------------------------------------------------+
1 row in set (0.00 sec)
Prøv:
SELECT
e.id,
e.dt_competition_last_manual_check,
MAX(ec.dt_created) as m,
# GREATEST always return NULL if present among arguments
NULLIF(
GREATEST(
COALESCE(MAX(ec.dt_created), '0000-00-00 00:00:00'),
COALESCE(e.dt_competition_last_manual_check, '0000-00-00 00:00:00')
)
, '0000-00-00 00:00:00') AS most_recent_dt_created_or_checked
FROM `estates` AS `e`
LEFT JOIN `estates` AS `ec` ON e.id = ec.estates_id_duplicate
WHERE e.server = 'esk'
GROUP BY `e`.`id`
ORDER BY most_recent_dt_created_or_checked DESC;