mysql - MySQL获取具有相同ID和相关孩子的父母

Question

假设我们有一个 mysql 表

Id    RelatedId
1     0
2     0
3     1
4     2
5     1
6     2

如何在单个 MySQL 查询中删除 RelatedId=0 的所有记录，然后删除 Id=RelatedId 上的子项？

Answer 1

ClaireG 的答案的替代方法是强制与设置为 ON DELETE CASCADE 的外键的关系。

Answer 2

您必须检查两次：

DELETE FROM [yourTableName] 
WHERE RelatedId = 0
   OR (RelatedId in 
         (select id from [yourTableName] where RelatedId = 0))

查找相关ID为空的所有记录，并查找与0相关的所有其他ID（在您的情况下[1,2]）

Answer 3

似乎有效...

DELETE
FROM
    delete_table
WHERE
    delete_table.RelatedId IN (
    select Id from(
        SELECT
            s1.Id
        FROM
            delete_table s1
        WHERE
            s1.RelatedId = 0
    ) as x
)
OR delete_table.RelatedId = 0;

Answer 4

DELETE TABLENAME 
FROM TABLENAME T1
WHERE TABLENAME.ID = T1.RELTED_ID AND T1.RELTED_ID = 0;