sql-server - SQL Server 2008 中不指定列名的 MERGE

Question

我正在查看 MERGE 命令，它看起来很酷，但仍然需要指定列。我正在寻找类似的东西:

MERGE INTO target AS t
USING source AS s          
WHEN MATCHED THEN
    UPDATE SET
    [all t.fields = s.fields]
WHEN NOT MATCHED THEN 
      INSERT ([all fields])
      VALUES ([all s.fields])

可能吗？

Answer 1

我很懒...这是我编写的一个便宜的过程，它将吐出表的通用 MERGE 命令。它查询 information_schema.columns 中的列名。我撕掉了我的源数据库名称 - 所以，你必须更新过程才能使用你的数据库(寻找@SourceDB ...我说它很便宜。)无论如何，我知道其他人可以写得更好 - 它为我服务目的很好。 (它做了几个假设，您可以将逻辑放入处理中 - 即关闭 IDENTITY_INSERT - 即使表没有标识列。)它会在当前上下文中更新表。它是针对 sql server 2008 编写的，用于同步一些表。当然，使用风险由您自行承担。

    CREATE PROCEDURE [dbo].[GenerateMergeSQL]
    @TableName varchar(100)
AS
BEGIN
    SET NOCOUNT ON 

    declare @sql varchar(5000),@SourceInsertColumns varchar(5000),@DestInsertColumns varchar(5000),@UpdateClause varchar(5000)
    declare @ColumnName varchar(100), @identityColName varchar(100)
    declare @IsIdentity int,@IsComputed int, @Data_Type varchar(50)

    declare @SourceDB as varchar(200)


    -- source/dest i.e. 'instance.catalog.owner.' - table names will be appended to this
    -- the destination is your current db context
    set @SourceDB = '[mylinkedserver].catalog.myDBOwner.'

    set @sql = ''
    set @SourceInsertColumns  = ''
    set @DestInsertColumns  = ''
    set @UpdateClause  = ''
    set @ColumnName  = ''
    set @isIdentity = 0
    set @IsComputed = 0
    set @identityColName  = ''
    set @Data_Type  = ''


DECLARE @ColNames CURSOR
SET @ColNames = CURSOR FOR 
    select column_name, COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') as IsIdentity ,
        COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsComputed') as IsComputed , DATA_TYPE
    from information_schema.columns where table_name = @TableName order by ordinal_position

OPEN @ColNames
FETCH NEXT FROM @ColNames INTO @ColumnName, @isIdentity, @IsComputed, @DATA_TYPE

WHILE @@FETCH_STATUS = 0
    BEGIN
        if @IsComputed = 0 and @DATA_TYPE <> 'timestamp'
        BEGIN
            set @SourceInsertColumns = @SourceInsertColumns + 
                case when @SourceInsertColumns = '' THEN '' ELSE ',' end +
                'S.' + @ColumnName

            set @DestInsertColumns = @DestInsertColumns + 
                case when @DestInsertColumns = '' THEN '' ELSE ',' end +
                @ColumnName

            if @isIdentity = 0
            BEGIN
                set @UpdateClause = @UpdateClause + 
                case when @UpdateClause = '' THEN '' ELSE ',' end
                 + @ColumnName + ' = ' + 'S.' + @ColumnName + char(10)
            END

            if @isIdentity = 1 set @identityColName = @ColumnName
        END

        FETCH NEXT FROM @ColNames INTO @ColumnName, @isIdentity, @IsComputed, @DATA_TYPE
    END

CLOSE @ColNames
DEALLOCATE @ColNames

    SET @sql = 'SET IDENTITY_INSERT ' + @TableName + ' ON;
            MERGE ' + @TableName + ' AS D
                USING ' + @SourceDB + @TableName + ' AS S
                ON (D.' + @identityColName + ' = S.' + @identityColName + ')
            WHEN NOT MATCHED BY TARGET
                THEN INSERT(' + @DestInsertColumns + ') 
                VALUES(' + @SourceInsertColumns + ')
            WHEN MATCHED 
                THEN UPDATE SET 
                    ' + @UpdateClause + '
            WHEN NOT MATCHED BY SOURCE
                THEN DELETE
            OUTPUT $action, Inserted.*, Deleted.*;
            SET IDENTITY_INSERT ' + @TableName + ' OFF'

    Print @SQL

END