又一表内公式计算应用实例
需求贴：http://topic.csdn.net/u/20100526/19/3aaa2ee0-7bb4-4c96-a6dd-a5811b2056d7.html?33002
现有一表Test如下
Id Flag Amt(float型)
1 A1 34
2 A2 45.2
3 A3 38
4 A4 83
5 A5 76.8
6 A6 23
7 A7 54
8 A8 11
9 A9 0.98
10 A10 23
现要求创建一个存储过程，向其中传入两个int变量而得到如下结果
(当传入4和2，两个值时，得到如下结果，4表示从这个Id号开始后四个依次的Id的Flag字段连接起来，
2表示从这个Id号开始后2个依次的Id的Flag字段连接起来，然后相减，Amt字段也是一样）
ID Desc Amt
1 A1+A2+A3+A4-(A1+A2) 121
2 A2+A3+A4+A5-(A2+A3) 159.8
3 A3+A4+A5+A6-(A3+A4) 99.8
4 A4+A5+A6+A7-(A4+A5) 77
5 A5+A6+A7+A8-(A5+A6) 65
6 A6+A7+A8+A9-(A6+A7) 11.98
7 A7+A8+A9+A10-(A7+A8) 23.98
当Id字段后面没有传入的值4那么多记录后，着不进行运算，比如上表中只有到ID为7的记录
----------------------------------------------------------------------------------
-- Author : htl258(Tony)
-- Date : 2010-05-26 21:55:20
-- Version: Microsoft SQL Server 2008 (RTM) - 10.0.1600.22 (Intel X86)
-- Jul 9 2008 14:43:34
-- Copyright (c) 1988-2008 Microsoft Corporation
-- Developer Edition on Windows NT 5.1 <X86> (Build 2600: Service Pack 2)
-- Blog : http://blog.csdn.net/htl258
----------------------------------------------------------------------------------
--> 生成测试数据表: [tb]
IF OBJECT_ID('[tb]') IS NOT NULL
DROP TABLE [tb]
GO
CREATE TABLE [tb] ([Id] [int],[Flag] [nvarchar](10),[Amt] [float])
INSERT INTO [tb]
SELECT '1','A1','34' UNION ALL
SELECT '2','A2','45.2' UNION ALL
SELECT '3','A3','38' UNION ALL
SELECT '4','A4','83' UNION ALL
SELECT '5','A5','76.8' UNION ALL
SELECT '7','A6','23' UNION ALL
SELECT '9','A7','54' UNION ALL
SELECT '11','A8','11' UNION ALL
SELECT '12','A9','0.98' UNION ALL
SELECT '13','A10','23'
-->SQL查询如下:
IF OBJECT_ID('P_TEST') IS NOT NULL
DROP PROC P_TEST
GO
CREATE PROC P_TEST @c1 int,
@c2 int
AS
SET NOCOUNT ON
DECLARE @S nvarchar(max),@S1 nvarchar(max),@I int
SET @I=1
WHILE @c1>=@I
BEGIN
SET @S=ISNULL(@S+'+','SELECT t1.Id,''(') +'''+t'+LTRIM(@I)+'.Flag+'''
SET @I=@I+1
END
SET @S=@S+')-('''
SET @I=1
WHILE @c2>=@I
BEGIN
SET @S=@S+'+t'+LTRIM(@I)+'.Flag+''+'''
SET @I=@I+1
END
SET @S=STUFF(@S,LEN(@S)-1,2,')''')+' [Desc],''('''
SET @I=1
WHILE @c1>=@I
BEGIN
SET @S=@S+'+LTRIM(t'+LTRIM(@I)+'.Amt)+''+'''
SET @I=@I+1
END
SET @S=STUFF(@S,LEN(@S)-2,2,''')-(')
SET @I=1
WHILE @c2>=@I
BEGIN
SET @S=@S+'+LTRIM(t'+LTRIM(@I)+'.Amt)+''+'''
SET @I=@I+1
END
SET @S=STUFF(@S,LEN(@S)-1,2,')''')+' [Amt1],Amt=CAST(0 AS Float)'
SET @I=2
WHILE @c1>=@I
BEGIN
SET @S1=ISNULL(@S1,' INTO # FROM [T] t1') +' JOIN [T] t'+LTRIM(@I)+' ON t'+LTRIM(@I-1)+'.ID=t'+LTRIM(@I)+'.ID-1'
SET @I=@I+1
END
SET @S1=@S1+'
DECLARE @S NVARCHAR(1000),@Id INT,@Amt Float
DECLARE C CURSOR FOR
SELECT ID,''SELECT @Amt=''+Amt1 FROM #
OPEN C
FETCH C INTO @Id,@S
WHILE @@FETCH_STATUS=0
BEGIN
EXEC SP_EXECUTESQL @S,N''@Amt Float OUT'',@Amt OUT
UPDATE # SET Amt=@Amt WHERE Id=@Id
FETCH C INTO @Id,@S
END
CLOSE C
DEALLOCATE C
SELECT ID,[Desc],Amt FROM #'
EXEC(';WITH T AS (SELECT ID=ROW_NUMBER()OVER(ORDER BY ID),[Flag],[Amt] FROM tb)'+ @S+@S1)
SET NOCOUNT OFF
GO
EXEC P_TEST 4,2
/*
ID Desc Amt
----------- --------------------------------------------------------------------- ----------------------
1 (A1+A2+A3+A4)-(A1+A2) 121
2 (A2+A3+A4+A5)-(A2+A3) 159.8
3 (A3+A4+A5+A6)-(A3+A4) 99.8
4 (A4+A5+A6+A7)-(A4+A5) 77
5 (A5+A6+A7+A8)-(A5+A6) 65
6 (A6+A7+A8+A9)-(A6+A7) 11.98
7 (A7+A8+A9+A10)-(A7+A8) 23.98
(7 行受影响)
*/
EXEC P_TEST 5,2
/*
ID Desc Amt
----------- -------------------------------------------------------------------------------- ----------------------
1 (A1+A2+A3+A4+A5)-(A1+A2) 197.8
2 (A2+A3+A4+A5+A6)-(A2+A3) 182.8
3 (A3+A4+A5+A6+A7)-(A3+A4) 153.8
4 (A4+A5+A6+A7+A8)-(A4+A5) 88
5 (A5+A6+A7+A8+A9)-(A5+A6) 65.98
6 (A6+A7+A8+A9+A10)-(A6+A7) 34.98
(6 行受影响)
*/