在SQL Server 2012中使用MERGE插入/更新数据

Question

我正在使用SQL Server 2012，并且具有两个结构相同的表。如果表2中还不存在新记录，我想将它们从表1插入表2。

如果它们已经存在，那么我想更新表2中的所有现有记录。

我的表中有大约30列，我想更新所有这些列。

有人可以帮忙吗？我查看了通过互联网发布的各种链接，但完全不了解我的声明的外观。

Answer 1

真的不那么难....

你需要：

• 源表（或查询）以提供数据
• 将其合并到的目标表
• 检查这两个表的条​​件
• 声明如果找到匹配项（在该条件下）该怎么办
• 声明如果找不到（在该条件下）匹配该怎么办

因此，基本上，它类似于：

-- this is your TARGET table - this is where the data goes into    
MERGE dbo.SomeTable AS target       
-- this is your SOURCE table where the data comes from 
USING dbo.AnotherTable AS source    
-- this is the CONDITION they have to "meet" on
ON (target.SomeColumn = source.AnotherColumn)

-- if there's a match, so if that row already exists in the target table,
-- then just UPDATE whatever columns in the existing row you want to update
WHEN MATCHED THEN                           
    UPDATE SET Name = source.Name,
               OtherCol = source.SomeCol

-- if there's NO match, that is the row in the SOURCE does *NOT* exist in the TARGET yet,
-- then typically INSERT the new row with whichever columns you're interested in
WHEN NOT MATCHED THEN  
    INSERT (Col1, Col2, ...., ColN)  
    VALUES (source.Val1, source.Val2, ...., source.ValN);