在mysql的語法中。修改或者刪除的時候不能直接調用子查詢的結果集。需要先給子查詢其別名。在調用。

比如：下面的去除重復項

DELETE FROM t_equipment_type t WHERE t.type = 2
AND (t.type_code,t.type_name) IN (
　　SELECT type_code,type_name FROM t_equipment_type
　　GROUP BY type_code, type_name HAVING COUNT(*) > 1)
AND t.rec_id NOT IN (
　　SELECT MIN(rec_id) FROM t_equipment_type
　　GROUP BY type_code, type_name HAVING COUNT(*) > 1)

這樣會報錯。

DELETE FROM t_equipment_type WHERE rec_id IN (
　　SELECT b.* FROM (
　　　　SELECT t.rec_id FROM t_equipment_type t WHERE t.type = 2
　　　　(t.type_code,t.type_name) IN (
　　　　　　SELECT type_code,type_name FROM t_equipment_type
　　　　　　GROUP BY type_code HAVING COUNT(*) > 1)
　　 AND t.rec_id NOT IN (
　　　　　　SELECT MIN(rec_id) rec_id FROM t_equipment_type
　　　　　　GROUP BY type_code,type_name HAVING COUNT(*) > 1)
　　　　) b

)

mysql的一個坑