SQL Server / T-SQL是否需要修改动态存储过程？

Question

我有一个存储过程，可以动态生成MERGE TSQL语句来处理给定的Dimension / Staging表转储之间的SCD Type 1更新。

这是T-SQL代码（从Alex Whittles的原始代码修改而来）：

USE [OPPY_DWUSD]
GO

ALTER PROCEDURE [dbo].[GenerateMerge]
/***************************************************************
*                                                              *
*   Script for use with blog post                              *
*     "Automating T-SQL Merge to load Dimensions (SCD)"        *
*     http://www.purplefrogsystems.com/blog/2012/04/automating-t-sql-merge-to-load-dimensions-scd
*                                                              *   
*   Posted: 6th April 2012                                     *
*                                                              *
*   By: Alex Whittles - Purple Frog Business Intelligence      *
*       www.PurpleFrogSystems.com                              *
*                                                              *
*   All code samples are provided “AS IS” without warranty of  *
*   any kind, either express or implied, including but not     *
*   limited to the implied warranties of merchantability       *
*   and/or fitness for a particular purpose.                   *
*                                                              *
***************************************************************/

@Dimension  varchar(50),
@Schema     varchar(50),
@ETLTable   varchar(50),
@ETLSchema  varchar(50),
@Execute    bit=0  --Should the resulting merge be returned or executed
AS
BEGIN
SET NOCOUNT ON;

--Create Carriage return variable to format the resulting query
DECLARE @crlf char(2)
SET @crlf = CHAR(13)


--Find out which Audit fields are used
DECLARE @UseIsInferred bit
DECLARE @UseFirstCreated bit
DECLARE @UseValidTo bit
DECLARE @UseIsRowCurrent bit
DECLARE @UseLastUpdated bit

SET @UseIsInferred = ISNULL((SELECT MAX(1) 
FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE       s.name = @Schema
        AND t.name = @Dimension
        AND c.name = 'IsInferred'
),0)

SET @UseFirstCreated= ISNULL((SELECT MAX(1) 
FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE       s.name = @Schema
        AND t.name = @Dimension
        AND c.name = 'FirstCreated'
),0)

SET @UseValidTo = ISNULL((SELECT MAX(1) 
FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE       s.name = @Schema
        AND t.name = @Dimension
        AND c.name = 'ValidTo'
),0)

SET @UseIsRowCurrent = ISNULL((SELECT MAX(1) 
FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE       s.name = @Schema
        AND t.name = @Dimension
        AND c.name = 'IsRowCurrent'
),0)

SET @UseLastUpdated = ISNULL((SELECT MAX(1) 
FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE       s.name = @Schema
        AND t.name = @Dimension
        AND c.name = 'LastUpdated'
),0)


--Identify the business key column(s)
--Also define what the null replacement should be
DECLARE myCurBK Cursor FOR 
SELECT c.name
    , CASE WHEN ty.name IN ('text', 'ntext', 'varchar', 'char', 'nvarchar', 'nchar') THEN ''''''
        WHEN ty.name IN ('tinyint', 'smallint', 'int', 'real', 'money', 'float', 'bit', 'decimal', 'numeric','smallmoney','bigint') THEN '0'
        WHEN ty.name IN ('date', 'datetime') THEN '''19000101'''
        ELSE 'NULL' END AS NullRep
FROM sys.columns c
    INNER JOIN sys.tables t on c.object_id = t.object_id
    INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
    INNER JOIN sys.types ty ON c.user_type_id = ty.user_type_id
    INNER JOIN sys.extended_properties ep 
         ON t.object_id=ep.major_id
        AND c.column_id=ep.minor_id
        AND ep.class=1
        AND ep.name='SCD'
WHERE s.name = @Schema
    AND t.name = @Dimension
    AND ep.value = 'BK'
ORDER BY c.column_id

--Identify all fields to be merged (Exclude Type 0)
DECLARE myCurType1 Cursor
FOR SELECT c.name
    , CASE WHEN ty.name IN ('text', 'ntext', 'varchar', 'char', 'nvarchar', 'nchar') THEN ''''''
        WHEN ty.name IN ('tinyint', 'smallint', 'int', 'real', 'money', 'float', 'bit', 'decimal', 'numeric','smallmoney','bigint') THEN '0'
        WHEN ty.name IN ('date', 'datetime') THEN '''19000101'''
        ELSE 'NULL' END AS NullRep
    FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
        INNER JOIN sys.types ty ON c.user_type_id = ty.user_type_id
        LEFT JOIN sys.extended_properties ep 
             ON t.object_id=ep.major_id
            AND c.column_id=ep.minor_id
            AND ep.class=1
            AND ep.name='SCD'
    WHERE s.name = @Schema
        AND t.name = @Dimension
        AND c.is_identity=0
        AND ISNULL(ep.value,'1') NOT IN ('0', 'Audit', 'BK')
    ORDER BY c.column_id ASC

--Identify all fields for insert
DECLARE myCurAll Cursor
FOR SELECT c.name
    , CASE WHEN ty.name IN ('text', 'ntext', 'varchar', 'char', 'nvarchar', 'nchar') THEN ''''''
        WHEN ty.name IN ('tinyint', 'smallint', 'int', 'real', 'money', 'float', 'bit', 'decimal', 'numeric','smallmoney','bigint') THEN '0'
        WHEN ty.name IN ('date', 'datetime') THEN '''19000101'''
        ELSE 'NULL' END AS NullRep
    FROM sys.columns c
        INNER JOIN sys.tables t on c.object_id = t.object_id
        INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
        INNER JOIN sys.types ty ON c.user_type_id = ty.user_type_id
    WHERE s.name = @Schema
        AND t.name = @Dimension
        AND c.name NOT IN ('LastUpdated', 'IsInferred', 'FirstCreated', 'ValidTo', 'IsRowCurrent')
        AND c.is_identity=0
    ORDER BY c.column_id ASC

DECLARE @Field varchar(255)
DECLARE @NullRep varchar(20)
DECLARE @SQL varchar(max)
DECLARE @SQL2 varchar(max)
DECLARE @SQL3 varchar(max)

--Now start building up the dynamic SQL

SET @SQL ='MERGE [' + @Schema + '].[' + @Dimension + '] AS Target'
SET @SQL = @SQL + @crlf + 'USING [' + @ETLSchema + '].[' + @ETLTable + '] AS Source'

OPEN myCurBK
FETCH NEXT FROM myCurBK INTO @Field, @NullRep
IF (@@FETCH_STATUS>=0)
    BEGIN
        SET @SQL = @SQL + @crlf + '       ON Target.' + '[' + @Field + ']' +  ' = Source.' + '[' + @Field + ']'
        FETCH NEXT FROM myCurBK INTO @Field, @NullRep
    END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
    IF (@@FETCH_STATUS<>-2)
        SET @SQL = @SQL + @crlf + '       AND Target.' + '[' + @Field + ']' +  ' = Source.' + '[' + @Field + ']'
    FETCH NEXT FROM myCurBK INTO @Field, @NullRep
END
CLOSE myCurBK

IF @UseIsRowCurrent>0   SET @SQL = @SQL + @crlf + '       AND Target.IsRowCurrent=1'

SET @SQL = @SQL + @crlf + '    WHEN MATCHED'

OPEN myCurType1
FETCH NEXT FROM myCurType1 INTO @Field, @NullRep

IF (@@FETCH_STATUS>=0)
    BEGIN
        SET @SQL = @SQL + @crlf + '       AND (ISNULL(Target.' + '[' + @Field + ']' + ',' + @NullRep + ') <> ISNULL(Source.' + '[' + @Field + ']' + ',' + @NullRep + ')'
        FETCH NEXT FROM myCurType1 INTO @Field, @NullRep
    END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
    IF (@@FETCH_STATUS<>-2)
        SET @SQL = @SQL + @crlf + '       OR ISNULL(Target.' + '[' + @Field + ']' + ',' + @NullRep + ') <> ISNULL(Source.' + '[' + @Field + ']' + ',' + @NullRep + ')'
    FETCH NEXT FROM myCurType1 INTO @Field, @NullRep
END
CLOSE myCurType1

SET @SQL = @SQL + @crlf + '      )'
SET @SQL2 = '    THEN UPDATE SET'

OPEN myCurType1
FETCH NEXT FROM myCurType1 INTO @Field, @NullRep
IF (@@FETCH_STATUS>=0)
    BEGIN
        SET @SQL2 = @SQL2 + @crlf + '       ' + '[' + @Field + ']' + ' = Source.' + '[' + @Field + ']'
        FETCH NEXT FROM myCurType1 INTO @Field, @NullRep
    END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
    IF (@@FETCH_STATUS<>-2)
        SET @SQL2 = @SQL2 + @crlf + '      ,' + '[' + @Field + ']' + ' = Source.' + '[' + @Field + ']'
    FETCH NEXT FROM myCurType1 INTO @Field, @NullRep
END
CLOSE myCurType1

IF @UseLastUpdated>0   SET @SQL2 = @SQL2 + @crlf + '      ,LastUpdated = GetDate()'

SET @SQL3 = '    WHEN NOT MATCHED THEN'
SET @SQL3 = @SQL3 + @crlf + '         INSERT ('

OPEN myCurAll
FETCH NEXT FROM myCurAll INTO @Field, @NullRep
IF (@@FETCH_STATUS>=0)
    BEGIN
        SET @SQL3 = @SQL3 + @crlf + '           ' + '[' + @Field + ']'
        FETCH NEXT FROM myCurAll INTO @Field, @NullRep
    END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
    IF (@@FETCH_STATUS<>-2)
        SET @SQL3 = @SQL3 + @crlf + '           ,' + '[' + @Field + ']'
    FETCH NEXT FROM myCurAll INTO @Field, @NullRep
END
CLOSE myCurAll


IF @UseIsInferred>0     SET @SQL3 = @SQL3 + @crlf + '           ,IsInferred'
IF @UseFirstCreated>0   SET @SQL3 = @SQL3 + @crlf + '           ,FirstCreated'
IF @UseValidTo>0        SET @SQL3 = @SQL3 + @crlf + '           ,ValidTo'
IF @UseIsRowCurrent>0   SET @SQL3 = @SQL3 + @crlf + '           ,IsRowCurrent'
IF @UseLastUpdated>0    SET @SQL3 = @SQL3 + @crlf + '           ,LastUpdated'
SET @SQL3 = @SQL3 + @crlf + '         ) VALUES ('

OPEN myCurAll
FETCH NEXT FROM myCurAll INTO @Field, @NullRep
IF (@@FETCH_STATUS>=0)
    BEGIN
        SET @SQL3 = @SQL3 + @crlf + '            Source.' + '[' + @Field + ']'
        FETCH NEXT FROM myCurAll INTO @Field, @NullRep
    END
WHILE (@@FETCH_STATUS<>-1)
BEGIN
    IF (@@FETCH_STATUS<>-2)
        SET @SQL3 = @SQL3 + @crlf + '           ,Source.' + '[' + @Field + ']'
    FETCH NEXT FROM myCurAll INTO @Field, @NullRep
END
CLOSE myCurAll    

IF @UseIsInferred>0     SET @SQL3 = @SQL3 + @crlf + '           ,0'
IF @UseFirstCreated>0   SET @SQL3 = @SQL3 + @crlf + '           ,GetDate()'
IF @UseValidTo>0        SET @SQL3 = @SQL3 + @crlf + '           ,NULL'
IF @UseIsRowCurrent>0   SET @SQL3 = @SQL3 + @crlf + '           ,1'
IF @UseLastUpdated>0    SET @SQL3 = @SQL3 + @crlf + '           ,GetDate()'
SET @SQL3 = @SQL3 + @crlf + '         );'

--clean up
DEALLOCATE myCurType1
DEALLOCATE myCurAll
DEALLOCATE myCurBK

IF @Execute = 1
BEGIN
    EXEC(@SQL + @SQL2 + @SQL3)           
END
ELSE
BEGIN    
    PRINT @SQL
    PRINT @SQL2
    PRINT @SQL3
END

END

在上面的存储过程中，当我传入变量时，它将产生以下代码：

MERGE [DIM].[COMPANY] AS Target
USING [DBO].[DWUSD_LIVE] AS Source
    ON Target.[comp] = Source.[comp]
 WHEN MATCHED
    AND (ISNULL(Target.[comp name],'') <> ISNULL(Source.[comp name],'')
    OR ISNULL(Target.[comp description],'') <> ISNULL(Source.[comp description],'')
   )
THEN UPDATE SET
    [comp name] = Source.[comp name]
   ,[comp description] = Source.[comp description]
   ,LastUpdated = GetDate()
WHEN NOT MATCHED THEN
      INSERT (
        [comp]
        ,[comp name]
        ,[comp description]
        ,FirstCreated
        ,LastUpdated
      ) VALUES (
         Source.[comp]
        ,Source.[comp name]
        ,Source.[comp description]
        ,GetDate()
        ,GetDate()
      );

我需要做的是在开头添加一个DISTINCT SELECT子查询...

MERGE [dim].[Company] AS Target
USING (
SELECT DISTINCT 
[COMP NAME],
[COMP DESCRIPTION],
[COMP]
FROM [dbo].[DWUSD_LIVE]
) AS Source

因此，当查看源（登台表）时，它将对维度中找到的相同列执行SELECT DISTINCT ，但不包括审核列（ FirstCreated / LastUpdated ）。

我的登台表有重复的记录，因此我只需要SELECT DISTINCT否则最终在我的维度中会有多个记录。

Answer 1

似乎您将要用作存储过程的表的表传递给了这些变量：

@ETLTable   varchar(50),
@ETLSchema  varchar(50),

这些相同的变量用于定义源：

--Now start building up the dynamic SQL

SET @SQL ='MERGE [' + @Schema + '].[' + @Dimension + '] AS Target'
SET @SQL = @SQL + @crlf + 'USING [' + @ETLSchema + '].[' + @ETLTable + '] AS Source'

我相信，只要您具有来自实际源表的相同列，就可以采用您要使用的独特查询，使用它创建一个视图并将该表传递给存储的proc。

CREATE VIEW dbo.vwDWUSD_LIVE
AS 
SELECT DISTINCT 
[COMP NAME],
[COMP DESCRIPTION],
[COMP]
FROM [dbo].[DWUSD_LIVE]
GO

exec语句类似于：

EXEC [dbo].[GenerateMerge] 'COMPANY', 'DIM', 'vwDWUSD_LIVE', 'DBO', 1

同样，您也不必修改存储的proc，看起来它可能会被其他进程调用，如果其他表也遇到这种情况，则可以应用类似的解决方案。