ERROR 1241（21000）和ERROR 1093（HY000）MYSQL子查詢的防止執行

Question

我這裏提供MySQL查詢： -

mysql> UPDATE tbl_driver SET active_flag=NULL WHERE Pk_driver_id = (SELECT Pk_driver_id FROM tbl_driver JOIN tbl_location ON tbl_driver.pk_driver_id = tbl_location.fk_driver_id WHERE updated_at <= NOW() - INTERVAL 3 MINUTE AND active_flag=1); 



ERROR 1093 (HY000): You can't specify target table 'tbl_driver' for update in FROM clause 

，所以我改變了我的子查詢選擇*：

mysql> UPDATE tbl_driver SET active_flag=NULL WHERE Pk_driver_id = (SELECT * FROM tbl_driver JOIN tbl_location ON tbl_driver.pk_driver_id = tbl_location.fk_driver_id WHERE updated_at <= NOW() - INTERVAL 3 MINUTE AND active_flag=1); 



ERROR 1241 (21000): Operand should contain 1 column(s). 

請幫我解決這個問題，提前致謝。

Answer 1

使用一個INNER JOIN而不是再選擇應該讓你更新工作：

UPDATE 
    tbl_driver 
INNER JOIN 
    tbl_location 
ON 
    tbl_driver.pk_driver_id = tbl_location.fk_driver_id 
SET tbl_driver.active_flag = NULL 
WHERE 
    updated_at <= NOW() - INTERVAL 3 MINUTE 
AND 
    tbl_driver.active_flag = 1; 

MySQL有目前（5.6版本）的use of subqueries in UPDATE statements限制：

Currently, you cannot update a table and select from the same table in a subquery.

Answer 2

您試圖將set與單行值相匹配，您希望將其與所有在子查詢中出現的值進行匹配，即使它始終爲單值。 IN是允許您匹配集合中的值的關鍵字。

UPDATE tbl_driver SET active_flag=NULL 
WHERE Pk_driver_id IN (
    SELECT Pk_driver_id FROM tbl_driver 
    JOIN tbl_location ON tbl_driver.pk_driver_id = tbl_location.fk_driver_id 
    WHERE updated_at <= NOW() - INTERVAL 3 MINUTE AND active_flag=1);