SQL Server中单行MERGE/upsert的语法

Question

我正在尝试在表上执行单行插入/更新,但所有示例都是针对集合.

任何人都可以修复我的语法:

MERGE member_topic ON mt_member = 0 AND mt_topic = 110
WHEN MATCHED THEN UPDATE SET mt_notes = 'test'
WHEN NOT MATCHED THEN INSERT (mt_member, mt_topic, mt_notes) VALUES (0, 110, 'test')

每个marc_s的解析是将单行转换为子查询 - 这使我认为MERGE命令并不真正用于单行upsert.

MERGE member_topic
USING (SELECT 0 mt_member, 110 mt_topic) as source
ON member_topic.mt_member = source.mt_member AND member_topic.mt_topic = source.mt_topic
WHEN MATCHED THEN UPDATE SET mt_notes = 'test'
WHEN NOT MATCHED THEN INSERT (mt_member, mt_topic, mt_notes) VALUES (0, 110, 'test');

Answer 1

我终于MERGE在SQL Server 2008中使用了Upsert语法.使用Jacob 想要做的事情(一个Upsert):

IF EXISTS(SELECT * FROM member_topic WHERE mt_member = 0 AND mt_topic = 110)
BEGIN
    --update existing row
    UPDATE member_topic SET mt_notes = 'test'
    WHERE mt_member = 0
    AND mt_topic = 110
END
ELSE
BEGIN
    --insert new row
    INSERT INTO member_topic (mt_member, mt_topic, mt_notes)
    VALUES (0, 110, 'test')
END

等效MERGE语法是:

MERGE member_topic
USING ( 
    VALUES (0, 110, 'test')
) AS foo (mt_member, mt_topic, mt_notes) 
ON member_topic.mt_member = foo.mt_member 
   AND member_topic.mt_topic = foo.mt_topic
WHEN MATCHED THEN
   UPDATE SET mt_notes = foo.mt_notes
WHEN NOT MATCHED THEN
   INSERT (mt_member, mt_topic, mt_notes)
   VALUES (foo.mt_member, foo.mt_topic, foo.mt_notes)
; --A MERGE statement must be terminated by a semi-colon (;).

Answer 2

基本上,你是在正确的轨道 - 但你错过了你想要合并数据的源 - 尝试这样的事情:

MERGE 
   member_topic AS target
USING 
   someOtherTable AS source
ON 
   target.mt_member = source.mt_member 
   AND source.mt_member = 0 
   AND source.mt_topic = 110
WHEN MATCHED THEN 
   UPDATE SET mt_notes = 'test'
WHEN NOT MATCHED THEN 
   INSERT (mt_member, mt_topic, mt_notes) VALUES (0, 110, 'test')
; 

单行MERGE没有特殊语法 - 您需要做的就是使用适当的子句.在ON子句中使用适当的条件,您可以将源限制为单行 - 没问题.

不要忘记尾随的分号!不开玩笑 - 这很重要!

请参阅此博客文章,了解非常好的介绍MERGE.