T-SQL MERGE - 找出它采取的行动-数据库问题

T-SQL MERGE - finding out which action it took(T-SQL MERGE - 找出它采取的行动)

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问题描述

我需要知道 MERGE 语句是否执行了 INSERT.在我的场景中，插入是 0 或 1 行.

I need to know if a MERGE statement performed an INSERT. In my scenario, the insert is either 0 or 1 rows.

测试代码:

DECLARE @t table (C1 int, C2 int)
DECLARE @C1 INT, @C2 INT

set @c1 = 1
set @c2 = 1

MERGE       @t as tgt
USING       (SELECT @C1, @C2) AS src (C1, C2)
ON          (tgt.C1 = src.C1)
    WHEN MATCHED AND tgt.C2 != src.C2 THEN
        UPDATE SET tgt.C2 = src.C2
    WHEN NOT MATCHED BY TARGET THEN
        INSERT VALUES (src.C1, src. C2)
    OUTPUT deleted.*, $action, inserted.*;

SELECT inserted.*

最后一行无法编译(没有作用域，与触发器不同).我无法访问@action 或输出.实际上，我不想要任何输出元数据.

The last line doesn't compile (no scope, unlike a trigger). I can't get access to @action, or the output. Actually, I don't want any output meta data.

我该怎么做?

推荐答案

您可以将 OUTPUT 输出到表变量中，然后从中检索.试试这个:

You can OUTPUT into a table variable and then retrieve from that. Try this:

DECLARE @t table (C1 int, C2 int)
DECLARE @C1 INT, @C2 INT
DECLARE @Output TABLE (DeletedC1 INT, DeletedC2 INT, ActionType VARCHAR(20), InsertedC1 INT, InsertedC2 INT)

set @c1 = 1
set @c2 = 1

MERGE       @t as tgt
USING       (SELECT @C1, @C2) AS src (C1, C2)
ON          (tgt.C1 = src.C1)
    WHEN MATCHED AND tgt.C2 != src.C2 THEN
        UPDATE SET tgt.C2 = src.C2
    WHEN NOT MATCHED BY TARGET THEN
        INSERT VALUES (src.C1, src. C2)
    OUTPUT deleted.*, $action, inserted.* INTO @Output;

SELECT * FROM @Output WHERE ActionType = 'INSERT'

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