Question

通过以下查询，我可以找到要删除的数据：

SELECT ab.id, ab.anlage_id, a.id
FROM `anlagetobedienung` AS ab
LEFT JOIN anlage_new AS a ON ab.`anlage_id` = a.id
WHERE a.id IS NULL

如何编写删除anlagetobedienung表中找到的记录的DELETE语句？

Answer 1

DELETE ab
FROM `anlagetobedienung` AS ab 
LEFT JOIN anlage_new AS a ON ab.`anlage_id` = a.id 
WHERE a.id IS NULL

Answer 2

通常我会说：

delete anlage_new 
where id in (
    SELECT  a.id
    FROM `anlagetobedienung` AS ab
    LEFT JOIN anlage_new AS a ON ab.`anlage_id` = a.id
    WHERE a.id IS NULL
)

即。删除标识要删除的记录的select结果中主键所在的行。

但是根据你的查询，那些id = NULL似乎没有任何意义。

您能提供一些示例数据吗？

编辑完成后，我会说这应该有效：

delete `anlagetobedienung` 
where id in (
    SELECT  ab.id
    FROM `anlagetobedienung` AS ab
    LEFT JOIN anlage_new AS a ON ab.`anlage_id` = a.id
    WHERE a.id IS NULL
)

注意：内部选择具有'ab.id'而不是'a.id'，它似乎是原始选择中唯一可能包含有用内容的列。

Answer 3

DELETE FROM anlagebedienung aDEL WHERE aDEL.id IN 
 (SELECT ab.id 
  FROM `anlagetobedienung` AS ab
  LEFT JOIN anlage_new AS a ON ab.`anlage_id` = a.id
  WHERE a.id IS NULL )

Answer 4

另一种可能的解决方案：

DELETE FROM anlagetobedienung A
WHERE
    NOT EXISTS (SELECT * FROM anlage_new AN WHERE AN.id = A.anlage_id)

如果MySQL支持DELETE FROM中的别名（在MS SQL中支持，但我知道某些主要的RDBMS不支持这个），那么你可以这样做：

DELETE ab
FROM
    anlagetobedienung AS ab
LEFT JOIN anlage_new AS a ON
    ab.anlage_id = a.id
WHERE
    a.id IS NULL

Answer 5

你可以这样做：

DELETE FROM anlagetobedienung ab
 WHERE NOT EXISTS (SELECT NULL
                     FROM anlage_new a
                    WHERE a.id = ab.anlage_id
                  )

如何删除左连接找到的记录

5 个答案: