子查询返回了多个值。使用merge和tsql

目前，我有一个使用游标的大型存储过程，其中有两个merge语句。简而言之，我想从一个大表填充两个表

现在，我对sql还是个新手，为了扩展我的知识，我读了不少书。在这项研究中，我遇到了许多话题，他们讨论了游标及其可能给出的性能问题

当前的SP（带游标）工作正常，但我一直试图在没有游标的情况下使用我的代码（其他POV），这让我非常恼火

所以现在我被这段垃圾代码困住了。我想这是不可能做到的方式，我想它，但嘿，我可以尝试的权利

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错误：子查询返回的值超过1。当子查询后跟=、！=、时，不允许这样做 删除select语句..下面的语句负责使用哪个表更新哪个表

MERGE CONTACTS as target
USING STAGING_CONTACTS as source

因此，您的查询可以如下所示

  UPDATE SET
        MAIL = MAIL ,
        and so on...
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (mail,name,brand,id)

   MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
        target.MAIL = source.MAIL,
      and so on..
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (source.all columns....)

您还可以使用如下所示的别名

  UPDATE SET
        MAIL = MAIL ,
        and so on...
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (mail,name,brand,id)

   MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
        target.MAIL = source.MAIL,
      and so on..
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (source.all columns....)

---

删除select语句..下面的语句负责使用哪个表更新哪个表

MERGE CONTACTS as target
USING STAGING_CONTACTS as source

因此，您的查询可以如下所示

  UPDATE SET
        MAIL = MAIL ,
        and so on...
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (mail,name,brand,id)

   MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
        target.MAIL = source.MAIL,
      and so on..
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (source.all columns....)

您还可以使用如下所示的别名

  UPDATE SET
        MAIL = MAIL ,
        and so on...
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (mail,name,brand,id)

   MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
        target.MAIL = source.MAIL,
      and so on..
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES (source.all columns....)

使用下面的脚本

MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
       target.MAIL =   source.MAIL ,
        target.NAME =  source.Name,
        target.BRAND = source.BRAND ,
        target.ID =    source.ID 
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES ( source.MAIL , source.Name, source.BRAND ,source.ID );

使用下面的脚本

MERGE CONTACTS as target
USING STAGING_CONTACTS as source
ON (target.ID = source.ID)
WHEN MATCHED THEN
    UPDATE SET
       target.MAIL =   source.MAIL ,
        target.NAME =  source.Name,
        target.BRAND = source.BRAND ,
        target.ID =    source.ID 
WHEN NOT MATCHED THEN 
    INSERT (MAIL, NAME, BRAND, CORESOLEIL_ID)
    VALUES ( source.MAIL , source.Name, source.BRAND ,source.ID );

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合并是一个有缺陷的实现，并且在以后出现潜在数据问题时很难调试。我绝不允许任何人在我们的生产数据库中使用它。最好先使用update语句，然后再使用Insert（顺序很重要）。合并是一个有缺陷的实现，并且在以后出现潜在数据问题时很难调试。我绝不允许任何人在我们的生产数据库中使用它。最好先使用update语句，然后再使用Insert（顺序很重要）