我需要在给定的一组大小@k中生成大小@n的所有组合。有人可以查看以下SQL并首先确定以下逻辑是否返回预期结果，第二个是否有更好的方法？
/*CREATE FUNCTION dbo.Factorial ( @x int )
RETURNS int
AS
BEGIN
DECLARE @value int
IF @x <= 1
SET @value = 1
ELSE
SET @value = @x * dbo.Factorial( @x - 1 )
RETURN @value
END
GO*/
SET NOCOUNT ON;
DECLARE @k int = 5, @n int;
DECLARE @set table ( [value] varchar(24) );
DECLARE @com table ( [index] int );
INSERT @set VALUES ('1'),('2'),('3'),('4'),('5'),('6');
SELECT @n = COUNT(*) FROM @set;
DECLARE @combinations int = dbo.Factorial(@n) / (dbo.Factorial(@k) * dbo.Factorial(@n - @k));
PRINT CAST(@combinations as varchar(max)) + ' combinations';
DECLARE @index int = 1;
WHILE @index <= @combinations
BEGIN
INSERT @com VALUES (@index)
SET @index = @index + 1
END;
WITH [set] as (
SELECT
[value],
ROW_NUMBER() OVER ( ORDER BY [value] ) as [index]
FROM @set
)
SELECT
[values].[value],
[index].[index] as [combination]
FROM [set] [values]
CROSS JOIN @com [index]
WHERE ([index].[index] + [values].[index] - 1) % (@n) BETWEEN 1 AND @k
ORDER BY
[index].[index];
答案 0 :(得分：57)
答案 1 :(得分：5)
请原谅这个额外的答案。我在my original answer中遇到了帖子字符限制。
以下是我的答案中图表的完整平均数值效果结果。
| Erik | Peter
N K | CPU Duration Reads Writes | CPU Duration Reads Writes
-- -- - ----- -------- ------ ------ - ----- -------- ------- ------
1 1 | 0 0 7 0 | 0 0 7 0
2 1 | 0 0 10 0 | 0 0 7 0
2 2 | 0 0 7 0 | 0 0 11 0
3 1 | 0 0 12 0 | 0 0 7 0
3 2 | 0 0 12 0 | 0 0 13 0
3 3 | 5 0 7 0 | 0 0 19 0
4 1 | 0 0 14 0 | 0 0 7 0
4 2 | 0 0 18 0 | 0 0 15 0
4 3 | 0 0 14 0 | 5 0 27 0
4 4 | 0 0 7 0 | 0 0 35 0
5 1 | 5 0 16 0 | 5 0 7 0
5 2 | 0 0 26 0 | 0 0 17 0
5 3 | 0 0 26 0 | 0 0 37 0
5 4 | 0 0 16 0 | 0 0 57 0
5 5 | 0 0 7 0 | 0 0 67 0
6 1 | 0 0 18 0 | 0 0 7 0
6 2 | 5 0 36 0 | 0 0 19 0
6 3 | 0 0 46 0 | 0 0 49 0
6 4 | 0 0 36 0 | 0 0 89 0
6 5 | 5 0 18 0 | 5 0 119 0
6 6 | 0 0 7 0 | 0 0 131 0
7 1 | 5 0 20 0 | 0 0 7 0
7 2 | 0 0 48 0 | 0 0 21 0
7 3 | 0 0 76 0 | 0 0 63 0
7 4 | 0 0 76 0 | 0 0 133 0
7 5 | 0 1 48 0 | 0 1 203 0
7 6 | 5 0 20 0 | 0 1 245 0
7 7 | 5 0 7 0 | 0 3 259 0
8 1 | 5 2 22 0 | 0 4 7 0
8 2 | 0 1 62 0 | 0 0 23 0
8 3 | 0 1 118 0 | 0 0 79 0
8 4 | 0 1 146 0 | 0 1 191 0
8 5 | 5 3 118 0 | 0 1 331 0
8 6 | 5 1 62 0 | 5 2 443 0
8 7 | 0 0 22 0 | 5 3 499 0
8 8 | 0 0 7 0 | 5 3 515 0
9 1 | 0 2 24 0 | 0 0 7 0
9 2 | 5 3 78 0 | 0 0 25 0
9 3 | 5 3 174 0 | 0 1 97 0
9 4 | 5 5 258 0 | 0 2 265 0
9 5 | 5 7 258 0 | 10 4 517 0
9 6 | 5 5 174 0 | 5 5 769 0
9 7 | 0 3 78 0 | 10 4 937 0
9 8 | 0 0 24 0 | 0 3 1009 0
9 9 | 0 1 7 0 | 0 4 1027 0
10 1 | 10 4 26 0 | 0 0 7 0
10 2 | 5 5 96 0 | 0 0 27 0
10 3 | 5 2 246 0 | 0 0 117 0
10 4 | 10 10 426 0 | 10 4 357 0
10 5 | 15 12 510 0 | 5 8 777 0
10 6 | 15 16 426 0 | 10 9 1281 0
10 7 | 10 4 246 0 | 10 9 1701 0
10 8 | 10 5 96 0 | 10 5 1941 0
10 9 | 5 4 26 0 | 10 7 2031 0
10 10 | 5 0 7 0 | 10 7 2051 0
11 1 | 10 8 28 0 | 0 0 7 0
11 2 | 15 11 116 0 | 0 0 29 0
11 3 | 21 24 336 0 | 10 3 139 0
11 4 | 21 18 666 0 | 5 2 469 0
11 5 | 21 20 930 0 | 5 3 1129 0
11 6 | 26 35 930 0 | 15 12 2053 0
11 7 | 20 14 666 0 | 5 25 2977 0
11 8 | 15 9 336 0 | 20 14 3637 0
11 9 | 10 7 116 0 | 21 27 3967 0
11 10 | 10 8 28 0 | 36 34 4086 0
11 11 | 5 8 7 0 | 15 15 4109 0
12 1 | 16 18 30 0 | 5 0 7 0
12 2 | 31 32 138 0 | 0 0 31 0
12 3 | 31 26 446 0 | 10 2 163 0
12 4 | 47 40 996 0 | 10 7 603 0
12 5 | 47 46 1590 0 | 21 17 1593 0
12 6 | 57 53 1854 0 | 31 30 3177 0
12 7 | 41 39 1590 0 | 31 30 5025 0
12 8 | 41 42 996 0 | 42 43 6609 0
12 9 | 31 26 446 0 | 52 52 7607 0
12 10 | 20 19 138 0 | 57 62 8048 0
12 11 | 15 17 30 0 | 72 64 8181 0
12 12 | 15 10 7 0 | 67 38 8217 0
13 1 | 31 32 32 0 | 0 0 7 0
13 2 | 21 25 162 0 | 0 0 33 0
13 3 | 36 34 578 0 | 5 2 189 0
13 4 | 57 65 1436 0 | 10 5 761 0
13 5 | 41 40 2580 0 | 10 10 2191 0
13 6 | 62 56 3438 0 | 31 32 4765 0
13 7 | 62 62 3438 0 | 57 53 8251 0
13 8 | 52 64 2580 0 | 52 47 11710 0
13 9 | 26 28 1436 0 | 93 96 14311 0
13 10 | 31 29 578 0 | 161 104 15891 0
13 11 | 36 35 162 0 | 129 99 16525 0
13 12 | 21 22 32 0 | 156 96 16383 0
13 13 | 26 30 7 0 | 166 98 16411 0
14 1 | 57 53 34 0 | 0 0 7 0
14 2 | 52 50 188 0 | 0 0 35 0
14 3 | 57 60 734 0 | 10 4 217 0
14 4 | 78 76 2008 0 | 15 8 945 0
14 5 | 99 97 4010 0 | 36 34 2947 0
14 6 | 120 125 6012 0 | 41 47 6951 0
14 7 | 125 119 6870 0 | 93 94 12957 0
14 8 | 135 138 6012 0 | 88 98 19821 0
14 9 | 78 153 4010 0 | 234 156 26099 0
14 10 | 94 92 2008 0 | 229 133 30169 0
14 11 | 83 90 734 0 | 239 136 32237 0
14 12 | 47 46 188 0 | 281 176 33031 0
14 13 | 52 53 34 0 | 260 167 32767 0
14 14 | 46 47 7 0 | 203 149 32797 0
15 1 | 83 83 36 0 | 0 0 7 0
15 2 | 145 139 216 0 | 0 2 37 0
15 3 | 104 98 916 0 | 0 2 247 0
15 4 | 135 135 2736 0 | 15 17 1157 0
15 5 | 94 97 6012 0 | 26 27 3887 0
15 6 | 192 188 10016 0 | 57 53 9893 0
15 7 | 187 192 12876 0 | 73 73 19903 0
15 8 | 286 296 12876 0 | 338 230 33123 0
15 9 | 208 207 10016 0 | 354 223 46063 0
15 10 | 140 143 6012 0 | 443 334 56143 0
15 11 | 88 86 2736 0 | 391 273 62219 0
15 12 | 73 72 916 0 | 432 269 65019 0
15 13 | 109 117 216 0 | 317 210 65999 0
15 14 | 156 187 36 0 | 411 277 66279 0
15 15 | 140 142 7 0 | 354 209 65567 0
16 1 | 281 281 38 0 | 0 0 7 0
16 2 | 141 146 246 0 | 0 0 39 0
16 3 | 208 206 1126 0 | 10 4 279 0
16 4 | 187 189 3646 0 | 15 13 1399 0
16 5 | 234 234 8742 0 | 42 42 5039 0
16 6 | 333 337 16022 0 | 83 85 13775 0
16 7 | 672 742 22886 0 | 395 235 30087 0
16 8 | 510 510 25746 0 | 479 305 53041 0
16 9 | 672 675 22886 0 | 671 489 78855 0
16 10 | 489 492 16022 0 | 859 578 101809 0
16 11 | 250 258 8742 0 | 719 487 117899 0
16 12 | 198 202 3646 0 | 745 483 126709 0
16 13 | 119 119 1126 0 | 770 506 130423 0
16 14 | 291 327 246 0 | 770 531 131617 0
16 15 | 156 156 38 0 | 713 451 131931 0
16 16 | 125 139 7 0 | 895 631 132037 0
17 1 | 406 437 40 0 | 0 0 7 0
17 2 | 307 320 278 0 | 0 0 41 0
17 3 | 281 290 1366 0 | 0 3 313 0
17 4 | 307 317 4766 0 | 31 28 1673 0
17 5 | 354 378 12382 0 | 41 45 6433 0
17 6 | 583 582 24758 0 | 130 127 18809 0
17 7 | 839 859 38902 0 | 693 449 43873 0
17 8 | 1177 1183 48626 0 | 916 679 82847 0
17 9 | 1031 1054 48626 0 | 1270 944 131545 0
17 10 | 828 832 38902 0 | 1469 1105 180243 0
17 11 | 672 668 24758 0 | 1535 1114 219217 0
17 12 | 422 422 12382 0 | 1494 991 244047 0
17 13 | 474 482 4766 0 | 1615 1165 256501 0
17 14 | 599 607 1366 0 | 1500 1042 261339 0
17 15 | 223 218 278 0 | 1401 1065 262777 0
17 16 | 229 228 40 0 | 1390 918 263127 0
17 17 | 541 554 7 0 | 1562 1045 263239 0
18 1 | 401 405 42 0 | 0 0 7 0
18 2 | 401 397 312 0 | 0 0 43 0
18 3 | 458 493 1638 0 | 5 6 349 0
18 4 | 583 581 6126 0 | 16 13 1981 0
18 5 | 697 700 17142 0 | 83 130 8101 0
18 6 | 792 799 37134 0 | 156 162 25237 0
18 7 | 1672 1727 63654 0 | 1098 751 62693 0
18 8 | 1598 1601 87522 0 | 1416 1007 126423 0
18 9 | 1849 1893 97246 0 | 2051 1522 214021 0
18 10 | 1963 2083 87522 0 | 2734 2103 311343 0
18 11 | 1411 1428 63654 0 | 2849 2352 398941 0
18 12 | 1042 1048 37134 0 | 3021 2332 462671 0
18 13 | 942 985 17142 0 | 3036 2314 499881 0
18 14 | 656 666 6126 0 | 3052 2177 517099 0
18 15 | 526 532 1638 0 | 2910 2021 523301 0
18 16 | 614 621 312 0 | 3083 2108 525015 0
18 17 | 536 551 42 0 | 2921 2031 525403 0
18 18 | 682 680 7 0 | 3141 2098 525521 0
19 1 | 885 909 44 0 | 0 0 7 0
19 2 | 1411 1498 348 0 | 0 0 45 0
19 3 | 880 887 1944 0 | 5 4 387 0
19 4 | 1119 1139 7758 0 | 26 25 2325 0
19 5 | 1120 1127 23262 0 | 73 72 10077 0
19 6 | 1395 1462 54270 0 | 453 387 33591 0
19 7 | 1875 1929 100782 0 | 1197 838 87941 0
19 8 | 2656 2723 151170 0 | 2255 1616 188803 0
19 9 | 3046 3092 184762 0 | 3317 2568 340053 0
19 10 | 3635 3803 184762 0 | 5171 4041 524895 0
19 11 | 2739 2774 151170 0 | 5577 4574 709737 0
19 12 | 3203 3348 100782 0 | 6182 5194 860987 0
19 13 | 1672 1750 54270 0 | 6458 5561 961849 0
19 14 | 1760 1835 23262 0 | 6177 4964 1016199 0
19 15 | 968 1006 7758 0 | 6266 4331 1039541 0
19 16 | 1099 1134 1944 0 | 6208 4254 1047379 0
19 17 | 995 1037 348 0 | 6385 4366 1049403 0
19 18 | 916 964 44 0 | 6036 4268 1049831 0
19 19 | 1135 1138 7 0 | 6234 4320 1049955 0
20 1 | 1797 1821 46 0 | 0 0 7 0
20 2 | 2000 2029 386 0 | 0 0 47 0
20 3 | 2031 2071 2286 0 | 10 6 427 0
20 4 | 1942 2036 9696 0 | 31 34 2707 0
20 5 | 2104 2161 31014 0 | 88 85 12397 0
20 6 | 2880 2958 77526 0 | 860 554 43675 0
20 7 | 3791 3940 155046 0 | 2026 1405 121285 0
20 8 | 5130 5307 251946 0 | 3823 2731 276415 0
20 9 | 6547 6845 335926 0 | 5380 4148 528445 0
20 10 | 7119 7357 369518 0 | 8271 6685 864455 0
20 11 | 5692 5803 335926 0 | 9557 8029 1234057 0
20 12 | 4734 4850 251946 0 | 11114 9504 1570067 0
20 13 | 3604 3641 155046 0 | 11551 10434 1822097 0
20 14 | 2911 2999 77526 0 | 12317 10822 1977227 0
20 15 | 2115 2134 31014 0 | 12806 10679 2054837 0
20 16 | 2041 2095 9696 0 | 13062 9115 2085935 0
20 17 | 2390 2465 2286 0 | 12807 9002 2095715 0
20 18 | 1765 1788 386 0 | 12598 8601 2098085 0
20 19 | 2067 2143 46 0 | 12578 8626 2098555 0
20 20 | 1640 1663 7 0 | 12932 9064 2098685 0
21 1 | 3374 3425 48 0 | 0 0 7 0
21 2 | 4031 4157 426 0 | 0 1 49 0
21 3 | 3218 3250 2666 0 | 10 5 469 0
21 4 | 3687 3734 11976 0 | 21 25 3129 0
21 5 | 3692 3735 40704 0 | 115 114 15099 0
21 6 | 4859 4943 108534 0 | 963 661 56079 0
21 7 | 6114 6218 232566 0 | 2620 1880 164701 0
21 8 | 8573 8745 406986 0 | 4999 3693 397355 0
21 9 | 11880 12186 587866 0 | 9047 6863 804429 0
21 10 | 13255 13582 705438 0 | 14358 11436 1392383 0
21 11 | 13531 13807 705438 0 | 18823 15502 2097909 0
21 12 | 12244 12400 587866 0 | 21834 18760 2803435 0
21 13 | 9406 9528 406986 0 | 23771 21274 3391389 0
21 14 | 7114 7180 232566 0 | 26677 24296 3798463 0
21 15 | 4869 4961 108534 0 | 26479 23998 4031117 0
21 16 | 4416 4521 40704 0 | 26536 22976 4139739 0
21 17 | 4380 4443 11976 0 | 26490 19107 4180531 0
21 18 | 3265 3334 2666 0 | 25979 17995 4192595 0
21 19 | 3640 3768 426 0 | 26186 17891 4195349 0
21 20 | 3234 3295 48 0 | 25688 17653 4195863 0
21 21 | 3156 3219 7 0 | 26140 17838 4195999 0
答案 2 :(得分：3)
一些动态SQL怎么样？
DECLARE @k int = 5, @n INT
IF OBJECT_ID('tempdb..#set') IS NOT NULL DROP TABLE #set
CREATE TABLE #set ( [value] varchar(24) )
INSERT #set VALUES ('1'),('2'),('3'),('4'),('5'),('6')
SET @n = @@ROWCOUNT
SELECT dbo.Factorial(@n) / (dbo.Factorial(@k) * dbo.Factorial(@n - @k)) AS [expected combinations]
-- let's generate some sql.
DECLARE
@crlf NCHAR(2) = NCHAR(13)+NCHAR(10)
, @sql NVARCHAR(MAX)
, @select NVARCHAR(MAX)
, @from NVARCHAR(MAX)
, @order NVARCHAR(MAX)
, @in NVARCHAR(MAX)
DECLARE @j INT = 0
WHILE @j < @k BEGIN
SET @j += 1
IF @j = 1 BEGIN
SET @select = 'SELECT'+@crlf+' _1.value AS [1]'
SET @from = @crlf+'FROM #set AS _1'
SET @order = 'ORDER BY _1.value'
SET @in = '[1]'
END
ELSE BEGIN
SET @select += @crlf+', _'+CONVERT(VARCHAR,@j)+'.value AS ['+CONVERT(VARCHAR,@j)+']'
SET @from += @crlf+'INNER JOIN #set AS _'+CONVERT(VARCHAR,@j)+' ON _'+CONVERT(VARCHAR,@j)+'.value > _'+CONVERT(VARCHAR,@j-1)+'.value'
SET @order += ', _'+CONVERT(VARCHAR,@j)+'.value'
SET @in += ', ['+CONVERT(VARCHAR,@j)+']'
END
END
SET @select += @crlf+', ROW_NUMBER() OVER ('+@order+') AS combination'
SET @sql = @select + @from
-- let's see how it looks
PRINT @sql
EXEC (@sql)
-- ok, now dump pivot and dump into a table for later use
IF OBJECT_ID('tempdb..#combinations') IS NOT NULL DROP TABLE #combinations
CREATE TABLE #combinations (
combination INT
, value VARCHAR(24)
, PRIMARY KEY (combination, value)
)
SET @sql
= 'WITH CTE AS ('+@crlf+@sql+@crlf+')'+@crlf
+ 'INSERT #combinations (combination, value)'+@crlf
+ 'SELECT combination, value FROM CTE a'+@crlf
+ 'UNPIVOT (value FOR position IN ('+@in+')) AS b'
PRINT @sql
EXEC (@sql)
SELECT COUNT(DISTINCT combination) AS [returned combinations] FROM #combinations
SELECT * FROM #combinations
为@k = 5生成以下查询：
SELECT
_1.value AS [1]
, _2.value AS [2]
, _3.value AS [3]
, _4.value AS [4]
, _5.value AS [5]
, ROW_NUMBER() OVER (ORDER BY _1.value, _2.value, _3.value, _4.value, _5.value) AS combination
FROM #set AS _1
INNER JOIN #set AS _2 ON _2.value > _1.value
INNER JOIN #set AS _3 ON _3.value > _2.value
INNER JOIN #set AS _4 ON _4.value > _3.value
INNER JOIN #set AS _5 ON _5.value > _4.value
然后将其展开并转储到表格中。
动态SQL很丑陋，你不能将它包装在UDF中，但生成的查询非常有效。
答案 3 :(得分：1)
首先创建此UDF ...
CREATE FUNCTION [dbo].[_ex_fn_SplitToTable] (@str varchar(5000), @sep char(1) = null)
RETURNS @ReturnVal table (n int, s varchar(5000))
AS
/*
Alpha Test
-----------
select * from [dbo].[_ex_fn_SplitToTable_test01]('abcde','')
*/
BEGIN
declare @str2 varchar(5000)
declare @sep2 char(1)
if LEN(ISNULL(@sep,'')) = 0
begin
declare @i int
set @i = 0
set @str2 = ''
declare @char varchar(1)
startloop:
set @i += 1
--print @i
set @char = substring(@str,@i,1)
set @str2 = @str2 + @char + ','
if LEN(@str) <= @i
goto exitloop
goto startloop
exitloop:
set @str2 = left(@str2,LEN(@str2) - 1)
set @sep2 = ','
--print @str2
end
else
begin
set @str2 = @str
set @sep2 = @sep
end
;WITH Pieces(n, start, stop) AS (
SELECT 1, 1, CHARINDEX(@sep2, @str2)
UNION ALL
SELECT n + 1, stop + 1, CHARINDEX(@sep2, @str2, stop + 1)
FROM Pieces
WHERE stop > 0
)
insert into @ReturnVal(n,s)
SELECT n,
SUBSTRING(@str2, start, CASE WHEN stop > 0 THEN stop-start ELSE 5000 END) AS s
FROM Pieces option (maxrecursion 32767)
RETURN
END
GO
然后创建此存储过程...
CREATE proc [CombinationsOfString]
(
@mystring varchar(max) = '0,5,10,15,20,25'
)
as
/*
ALPHA TEST
---------
exec CombinationsOfString '-20,-10,0,10,20'
*/
if object_id('tempdb..#_201606070947_myorig') is not null drop table #_201606070947_myorig
CREATE TABLE #_201606070947_myorig
(
SourceId int not null identity(1,1)
,Element varchar(100) not null
)
insert into #_201606070947_myorig
select s from dbo._ex_fn_SplitToTable(@mystring,',')
--select SourceId, Element from #_201606070947_myorig
declare @mynumerics varchar(max)
set @mynumerics = (
select STUFF(REPLACE((SELECT '#!' + LTRIM(RTRIM(SourceId)) AS 'data()'
FROM #_201606070947_myorig
FOR XML PATH('')),' #!',', '), 1, 2, '') as Brands
)
set @mynumerics = REPLACE(@mynumerics,' ','')
print @mynumerics
if object_id('tempdb..#_201606070947_source') is not null drop table #_201606070947_source
if object_id('tempdb..#_201606070947_numbers') is not null drop table #_201606070947_numbers
if object_id('tempdb..#_201606070947_results') is not null drop table #_201606070947_results
if object_id('tempdb..#_201606070947_processed') is not null drop table #_201606070947_processed
CREATE TABLE #_201606070947_source
(
SourceId int not null identity(1,1)
,Element char(1) not null
)
--declare @mynumerics varchar(max)
--set @mynumerics = '1,2,3,4,5'
insert into #_201606070947_source
select s from dbo._ex_fn_SplitToTable(@mynumerics,',')
-- select * from #_201606070947_source
declare @Length int
set @Length = (select max(SourceId) from #_201606070947_source)
declare @columnstring varchar(max) = (SELECT REPLICATE('c.',@Length))
print @columnstring
declare @subs varchar(max) = (SELECT REPLICATE('substring.',@Length))
print @subs
if object_id('tempdb..#_201606070947_columns') is not null drop table #_201606070947_columns
select s+CONVERT(varchar,dbo.PadLeft(convert(varchar,n),'0',3)) cols
into #_201606070947_columns
from [dbo].[_ex_fn_SplitToTable](@columnstring,'.') where LEN(s) > 0
if object_id('tempdb..#_201606070947_subcolumns') is not null drop table #_201606070947_subcolumns
select s+'(Combo,'+CONVERT(varchar,n)+',1) ' + 'c'+CONVERT(varchar,dbo.PadLeft(convert(varchar,n),'0',3)) cols
into #_201606070947_subcolumns
from [dbo].[_ex_fn_SplitToTable](@subs,'.') where LEN(s) > 0
-- select * from #_201606070947_subcolumns
-- select * from #_201606070947_columns
declare @columns_sql varchar(max)
set @columns_sql =
(
select distinct
stuff((SELECT distinct + cast(cols as varchar(50)) + ' VARCHAR(1), '
FROM (
select cols
from #_201606070947_columns
) t2
--where t2.n = t1.n
FOR XML PATH('')),3,0,'')
from (
select cols
from #_201606070947_columns
) t1
)
declare @substring_sql varchar(max)
set @substring_sql =
(
select distinct
stuff((SELECT distinct + cast(cols as varchar(100)) + ', '
FROM (
select cols
from #_201606070947_subcolumns
) t2
--where t2.n = t1.n
FOR XML PATH('')),3,0,'')
from (
select cols
from #_201606070947_subcolumns
) t1
)
set @substring_sql = left(@substring_sql,LEN(@substring_sql) - 1)
print @substring_sql
set @columns_sql = LEFT(@columns_sql,LEN(@columns_sql) - 1)
--SELECT @columns_sql
declare @sql varchar(max)
set @sql = 'if object_id(''tempdb..##_201606070947_01'') is not null drop table ##_201606070947_01 create table ##_201606070947_01 (rowid int,' + @columns_sql + ')'
print @sql
execute(@sql)
CREATE TABLE #_201606070947_numbers (Number int not null)
insert into #_201606070947_numbers
select SourceId from #_201606070947_source
CREATE TABLE #_201606070947_results
(
Combo varchar(10) not null
,Length int not null
)
SET NOCOUNT on
DECLARE
@Loop int
,@MaxLoop int
-- How many elements there are to process
SELECT @MaxLoop = max(SourceId)
from #_201606070947_source
-- Initialize first value
TRUNCATE TABLE #_201606070947_results
INSERT #_201606070947_results (Combo, Length)
select Element, 1
from #_201606070947_source
where SourceId = 1
SET @Loop = 2
-- Iterate to add each Element after the first
WHILE @Loop <= @MaxLoop
BEGIN
INSERT #_201606070947_results (Combo, Length)
select distinct
left(re.Combo, @Loop - nm.Number)
+ so.Element
+ RIGHT(re.Combo, nm.Number - 1)
,@Loop
from #_201606070947_results re
inner join #_201606070947_numbers nm
on nm.Number <= @Loop
inner join #_201606070947_source so
on so.SourceId = @Loop
where re.Length = @Loop - 1
SET @Loop = @Loop + 1
END
-- select * from #_201606070947_results
-- Show #_201606070947_results
SELECT *
into #_201606070947_processed
from #_201606070947_results
where Length = @MaxLoop
order by Combo
-- select * from #_201606070947_processed
set @sql = 'if object_id(''tempdb..##_201606070947_02'') is not null drop table ##_201606070947_02 '
print @sql
execute(@sql)
set @sql = ' ' +
' SELECT ROW_NUMBER() OVER(ORDER BY Combo Asc) AS RowID,' + @substring_sql +
' into ##_201606070947_02 ' +
' FROM #_201606070947_processed ' +
' '
PRINT @sql
execute(@sql)
declare @columns_sql_new varchar(max)
set @columns_sql_new = REPLACE(@columns_sql,'(1)','(100)')
set @sql = 'if object_id(''tempdb..##_201606070947_03'') is not null drop table ##_201606070947_03 create table ##_201606070947_03 (RowId int,' + @columns_sql_new + ')'
PRINT @sql
execute(@sql)
insert into ##_201606070947_03 (RowId)
select RowId from ##_201606070947_02
--select * from ##_201606070947_03
DECLARE @ColumnId varchar(10)
DECLARE @getColumnId CURSOR
SET @getColumnId = CURSOR FOR
select cols ColumnId from #_201606070947_columns
OPEN @getColumnId
FETCH NEXT
FROM @getColumnId INTO @ColumnId
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT @ColumnId
set @sql = ' ' +
' update ##_201606070947_03
set ' + @ColumnId + ' = B.Element
from ##_201606070947_03 A
, (
select A.RowID, B.*
from
(
select * from ##_201606070947_02
) A
,
(
select * from #_201606070947_myorig
) B
where A.' + @ColumnId + ' = B.SourceId
) B
where A.RowId = B.RowId
'
execute(@sql)
print @sql
FETCH NEXT
FROM @getColumnId INTO @ColumnId
END
CLOSE @getColumnId
DEALLOCATE @getColumnId
select * from ##_201606070947_03
答案 4 :(得分：1)
group by子句的 CUBE 扩展表示给定列表的所有组合。例如，以下内容将给出4个元素集的所有3个组合。
select concat(a,b,c,d)
from (select 'a','b','c','d') as t(a,b,c,d)
group by cube(a,b,c,d)
having len(concat(a,b,c,d)) = 3
答案 5 :(得分：0)
我遇到了另一种计算组合的技巧，它非常简单。在公共SQL挑战中，它也完全胜过我自己的尝试，基于与我（当前）接受的答案相同的位模式技术。虽然我承认我没有超长时间玩它，或者从这里抓住我最好的解决方案并适应，但我再次写了它。
无论如何，我确信自己已经把自己钉在了一个钉子上 - 在这里，我想我已经找到了一些非常酷的东西但后来发现我的解决方案很容易被超越。但令我惊讶的是，当我尝试使用该技术时，它比上面的最佳方法更糟糕。它可供参考，因为它易于实现，并且对于小型作业具有合理的性能（因此除非工作可能要求增加复杂的位模式技术，否则它会更优越。）
给定一个表#Set，其行数与选择的项目相同，并且变量@K表示一次采取的项目数量，这是方法：
WITH Chains AS (
SELECT
Generation = 1,
Chain = Convert(varchar(1000),'|' + Value + '|'),
Value
FROM
#Set
WHERE
@K > 0
AND value <= ALL (
SELECT TOP (@K) Value
FROM #Set
ORDER BY Value DESC
)
UNION ALL
SELECT
C.Generation + 1,
Convert(varchar(1000), C.Chain + S.Value + '|'),
S.Value
FROM
Chains C
INNER JOIN #Set S
ON C.Value < S.Value
WHERE
C.Generation <= @K
)
SELECT
C.Chain,
S.Value
FROM
Chains C
INNER JOIN #Set S
ON C.Chain LIKE '%|' + S.Value + '|%'
WHERE
Generation = @K;