SQL Server 中单行 MERGE/upsert 的语法

2021-12-27 00:00:00 merge upsert sql-server

我正在尝试对表进行单行插入/更新，但所有示例都是针对集合的.

I'm trying to do a single row insert/update on a table but all the examples out there are for sets.

谁能修复我的语法:

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 的解决方案是将单行转换为子查询 - 这让我认为 MERGE 命令并不是真正用于单行 upserts.

Resolution per marc_s is to convert the single row to a subquery - which makes me think the MERGE command is not really intended for single row upserts.

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');

推荐答案

基本上，您走在正确的轨道上 - 但您缺少要合并数据的来源 - 尝试如下操作:

Basically, you're on the right track - but you're missing a source from where you want to merge the data - try something like this:

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 没有特殊的语法——您需要做的就是使用适当的子句.使用 ON 子句中的适当条件，您可以将源限制为单行 - 没问题.

There is no special syntax for a single row MERGE - all you need to do is use a proper clause. With that proper condition in the ON clause, you can limit the source to a single row - no problem.

不要忘记结尾的分号！不是开玩笑 - 这很重要！

And don't forget the trailing semicolon! No joke - it's important!

请参阅这篇博文 对 MERGE 的非常好的介绍.

See this blog post for a really good intro to MERGE.

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