行转列问题(案例)

来源：cnblogs　　作者：Insus.NET　　时间：2019/5/30 8:54:48　　对本文有异议

有网友在网上问：

数据如下：

number  createdate                         username         caseno
1       2018-05-29 18:57:54.150    戴婷                 201708220028
2      2018-07-04 14:28:40.167    戴婷                 201708220028
3     2019-01-02 11:34:53.533    戴婷         201708220028
4     2019-01-16 18:17:01.313    戴婷                201708220028

期望得到的结果：

username   caseno                     createdate1                             createdate2                           createdate3                         createdate4
戴婷               201708220028          2018-05-29 18:57:54.150      2018-07-04 14:28:40.167       2019-01-02 11:34:53.533     2019-01-16 18:17:01.313

下面是Insus.NET实现方法：

创建一个临时表，将用来存储最终结果：

IF OBJECT_ID('tempdb..#TempRpt') IS NOT NULL DROP TABLE #TempRpt   
CREATE TABLE #TempRpt
(   
    [caseno] bigint,
    [username] nvarchar(20)
)        
SELECT [caseno],[username] FROM #TempRpt

Source Code

接下来，参考这篇《数据表列值转换为逗号分隔字符串》https://www.cnblogs.com/insus/p/10848578.html

改写一下：

SET ANSI_NULLS ON
GO
 
SET QUOTED_IDENTIFIER ON
GO
 
-- =============================================
-- Author:      Insus.NET
-- Create date: 2019-05-29
-- Update date: 2019-05-29
-- Description: 时间表列值转换为逗号分隔字符串
-- =============================================
CREATE PROCEDURE [dbo].[usp_DateColumnToCommaDelimitedString] (
    @TableName SYSNAME, 
    @DateColumn    SYSNAME,
    @Comma_Delimited_String NVARCHAR(MAX) OUTPUT
)    
AS
BEGIN    
    DECLARE @query NVARCHAR(MAX) = N'SET @Comma_Delimited_String = STUFF((SELECT DISTINCT '','' + QUOTENAME(CAST('+ @DateColumn +' AS DATE)) 
            FROM '+ @TableName +'             
            FOR XML PATH(''''), TYPE
            ).value(''.'', ''NVARCHAR(MAX)'') 
        ,1,1,'''')'
 
    EXECUTE sp_executeSql @query, N'@Comma_Delimited_String AS NVARCHAR(MAX) OUTPUT',@Comma_Delimited_String OUTPUT
END
GO

Source Code

运行示例，并得到结果：

DECLARE @cols NVARCHAR(MAX)
EXECUTE[dbo].[usp_DateColumnToCommaDelimitedString] #T,createdate,@cols OUTPUT

Source Code

再接下来，再参考另外一篇《动态为表添加存储时间字段》https://www.cnblogs.com/insus/p/10943614.html

EXECUTE [dbo].[usp_DyanmicallyAddStorageDatetimeField] 'tempdb','dbo','#TempRpt',@cols    
 
EXECUTE('SELECT [caseno],[username],'+ @cols +' FROM #TempRpt')

Source Code

一切准备好，我们可以开始处理原始数据：

DECLARE @r INT = 1,@rs INT = 0
SELECT @rs = MAX([number]) FROM #T
WHILE @r <= @rs
BEGIN
    DECLARE @COLUMN_NAME SYSNAME,@createdate datetime,@username nvarchar(20),@caseno bigint
    SELECT @COLUMN_NAME = CONVERT(VARCHAR(30),[createdate], 23),@createdate = [createdate],@username = [username],@caseno = [caseno] FROM #T WHERE [number] = @r
 
 
    IF EXISTS(SELECT TOP 1 1 FROM #TempRpt WHERE [caseno] = @caseno)
        EXECUTE('UPDATE #TempRpt SET ['+ @COLUMN_NAME +']  = '''+ @createdate +''' WHERE [caseno] = '''+ @caseno +'''' )
    ELSE
        EXECUTE('INSERT INTO #TempRpt ([caseno],[username],['+ @COLUMN_NAME +']) VALUES('''+ @caseno +''',N'''+ @username +''','''+ @createdate +''')')    
    SET @r = @r + 1
END
 
EXECUTE('SELECT [caseno],[username],'+ @cols +' FROM #TempRpt')