MS SQL 删除所有不相等的记录

Question

我的问题是：我有 2 个表（例如 T1 和 T2）它们都有字段 Q_ID。 Table T1 在 Q_ID 列中有一些记录不符合 T2。我的目标是将它们与关系联系起来，所以我想删除 T2 中的所有行，其中 Q_ID 不会从 T1 中匹配 Q_ID。我试过像这样使用内部连接，但这个脚本只是删除了所有记录。

    DELETE dst FROM HRM_MVC_DEV_Test.dbo.ProjectWorkers as dst 
    INNER JOIN HRM_MVC_DEV_Test.dbo.Project as src on dst.ProjectId<>src.ProjectId

我正在使用 MS SQL 服务器 2014

Answer 1

可能是这样的：

CREATE TABLE T1 (ID INT, SomeValue VARCHAR(100));
CREATE TABLE T2 (ID INT, SomeValue VARCHAR(100));
INSERT INTO T1 VALUES
(1,'Row 1'),(2,'Row 2'),(3,'Row 3'),(4,'Row 4');
INSERT INTO T2 VALUES
(1,'Row 1'),(4,'Row 4');

DELETE FROM T1
WHERE T1.ID NOT IN(SELECT T2.ID FROM T2);

SELECT * FROM T1;
SELECT * FROM T2;

Answer 2

您也可以通过以下任一方式进行：

DELETE dst 
FROM HRM_MVC_DEV_Test.dbo.ProjectWorkers AS dst 
LEFT JOIN HRM_MVC_DEV_Test.dbo.Project AS src ON src.ProjectId = dst.ProjectId
WHERE src.ProjectId IS NULL

--第二个

DELETE dst 
FROM HRM_MVC_DEV_Test.dbo.ProjectWorkers AS dst 
WHERE NOT EXISTS(
    SELECT src.ProjectId FROM HRM_MVC_DEV_Test.dbo.Project AS src WHERE src.ProjectId = dst.ProjectId
)

Answer 3

DELETE
FROM HRM_MVC_DEV_Test.dbo.ProjectWorkers
WHERE NOT EXISTS (SELECT 1 FROM HRM_MVC_DEV_Test.dbo.Project WHERE Project.ProjectId = ProjectWorkers.ProjectId)

您可以使用 NOT EXISTS like the above. From the documentation:

NOT EXISTS works the opposite of EXISTS. The WHERE clause in NOT EXISTS is satisfied if no rows are returned by the subquery.

MS SQL 删除所有不相等的记录

MS SQL Delete all unequal record

sql

tsql

sql-server

sql-delete

sql-server-2014