MySQL 删除具有引用不存在 ID 的参数的行

Question

我需要从 table 中删除所有具有 "for_id" 参数的记录，指的是 "id" 不存在于此 table 中。

In this example，我需要删除带有 name =" tom " 的行，因为带有 id = 3 的条目不存在。

谢谢！

Answer 1

因此您想要 remove for_id 在 id
中 not exist 的那些记录换句话说，keep for_id 在 id

中 exists 的那些记录

SELECT * FROM table_name 
where for_id in (select id from table_name)

或使用join:

SELECT t1.* FROM 
table_name t1 join table_name t2
on t1.for_id=t2.id

输出：

| id | for_id | lvl | name |
|----|--------|-----|------|
|  4 |      1 |   1 |  joe |
|  5 |      1 |   1 | mack |
|  6 |      5 |   2 | bill |
|  7 |      5 |   2 |  rex |
|  8 |      7 |   3 |  ted |

Answer 2

如果你也想删除那些 for_id=0 那么你可以使用：

DELETE 
FROM table_name as t1
where not exists (select id 
       from table_name as t2 
       where t2.id=t1.for_id)

如果您不想删除 for_id=0 的那些，您可以使用：

delete 
FROM table_name as t1
where not exists (select id 
       from table_name as t2 
       where t2.id=t1.for_id) and t1.for_id<>0

Answer 3

DELETE D.* FROM table_name D
  LEFT JOIN table_name T
    ON T.ID=D.FOR_ID
 WHERE T.ID IS NULL and D.FOR_ID<>0;

测试 sqlfiddle.com

MySQL 删除具有引用不存在 ID 的参数的行

MySQL delete rows that have parameter which refers to the not exist ID

mysql

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exists