我有一个存储过程，它动态生成MERGETSQL 语句来处理给定 Dimension / Staging 表转储之间的 SCD 类型 1 更新。
这是 T-SQL 代码（由 Alex Whittles 修改自原始代码）：
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，它会生成以下代码：
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DISTINCT SELECT在开头添加一个子查询......
MERGE [dim].[Company] AS Target
USING (
SELECT DISTINCT
[COMP NAME],
[COMP DESCRIPTION],
[COMP]
FROM [dbo].[DWUSD_LIVE]
) AS Source
因此，当它查看源（临时表）时，它会SELECT DISTINCT在维度中找到的相同列上执行 a，但不包括审计列 ( FirstCreated/ LastUpdated)。
我的临时表有重复的记录，因此我只需要SELECT DISTINCT否则我的维度中有多个记录。