查詢結果null排到最後面

mysql 的order by 查詢默認是會將null排到有值的數據前面的。若想將null放最後面。則需要加上個null的order 控制
例如

 SELECT userid,  `migrate_time` 
FROM member
WHERE STATUS =0
AND id =3
ORDER BY (
update_time IS NULL
), update_time ASC 
LIMIT 0 , 30

SELECT * FROM your_table ORDER BY (date_column IS NULL), date_column ASC

參考：http://stackoverflow.com/questions/8510632/php-mysql-order-by-date-but-empty-dates-last-not-first