SQL DELETE 并 JOIN 另一个表作为 WHERE 条件

我必须从中删除行guide_category与 没有关系的guide表（死关系）。

这就是我想做的，但它当然行不通。

DELETE FROM guide_category AS pgc 
 WHERE pgc.id_guide_category IN (SELECT id_guide_category 
                                   FROM guide_category AS gc
                              LEFT JOIN guide AS g ON g.id_guide = gc.id_guide
                                  WHERE g.title IS NULL)

Error:

您无法在 FROM 子句中指定用于更新的目标表“guide_category”

由于锁定实现问题，MySQL不允许引用受影响的表DELETE or UPDATE.

你需要做一个JOIN在这里：

DELETE  gc.*
FROM    guide_category AS gc 
LEFT JOIN
        guide AS g 
ON      g.id_guide = gc.id_guide
WHERE   g.title IS NULL

或者只是使用NOT IN:

DELETE  
FROM    guide_category AS gc 
WHERE   id_guide NOT IN
        (
        SELECT  id_guide
        FROM    guide
        )