通过索引 and/or ID 有条件地加入 table

Question

这个table代表了一系列文档的重印。比如IdentifierBySet 1054已经打印了8次，而149141只打印了一次。我需要加入 table 并获取父 DocumentID，在第 8 次打印 IdentifierBySet 1054 的情况下，父 DocumentID 是 IndexBySet 7 处 DocumentID 的值，即来自 IndexBySet 值的前面的 IndexBySet return从联接编辑。对于 IdentifierBySet 149141，它只有一个值，因此父 DocumentID 是 IndexBySet 1 处的 DocumentID。我如何使此连接和 return 有条件地成为所需的值？

DECLARE @tbl TABLE
(IdentifierBySet varchar(10), IndexBySet int, DocumentID UNIQUEIDENTIFIER)

INSERT INTO @tbl
SELECT 1054, 1, 'FF5A398E-F6D7-4A8D-97B2-FBF1E6ED095B'
UNION
SELECT 1054, 2, 'B8A08EE1-302C-4865-AD9A-1AA559597F86'
UNION
SELECT 1054, 3, '7C7D7FC0-7C41-4283-936C-36599FADF695'
UNION
SELECT 1054, 4, '6F53B845-2107-4757-99EC-56B9DD76E300'
UNION
SELECT 1054, 5, '9E0CC5CE-1B7D-4D19-AFE7-E7849843CC2A'
UNION
SELECT 1054, 6, '6209881F-EDDE-4E69-955E-B29BE9913A2E'
UNION
SELECT 1054, 7, 'D0C5C822-B53B-4BA0-8923-6662F08FCF8A'
UNION
SELECT 1054, 8, '0A0C1281-B130-4E98-9551-5E64731D91DB'
UNION
SELECT 149141, 1, '041908FD-7B8B-4542-8F1A-1E453DE9D5BE'
UNION
SELECT 171251, 1, '65AB2C7B-B569-4E18-B53E-F6E15179990B'
UNION
SELECT 171251, 2, '0D245369-3C8D-4490-9708-214D5BAA913A'

SELECT * FROM @tbl

IdentifierBySet IndexBySet  DocumentID
1054            1           FF5A398E-F6D7-4A8D-97B2-FBF1E6ED095B
1054            2           B8A08EE1-302C-4865-AD9A-1AA559597F86
1054            3           7C7D7FC0-7C41-4283-936C-36599FADF695
1054            4           6F53B845-2107-4757-99EC-56B9DD76E300
1054            5           9E0CC5CE-1B7D-4D19-AFE7-E7849843CC2A
1054            6           6209881F-EDDE-4E69-955E-B29BE9913A2E
1054            7           D0C5C822-B53B-4BA0-8923-6662F08FCF8A
1054            8           0A0C1281-B130-4E98-9551-5E64731D91DB
149141          1           041908FD-7B8B-4542-8F1A-1E453DE9D5BE
171251          1           65AB2C7B-B569-4E18-B53E-F6E15179990B
171251          2           0D245369-3C8D-4490-9708-214D5BAA913A

预期结果

IdentifierBySet IndexBySet  DocumentID
1054            7           D0C5C822-B53B-4BA0-8923-6662F08FCF8A
149141          1           041908FD-7B8B-4542-8F1A-1E453DE9D5BE
171251          1           65AB2C7B-B569-4E18-B53E-F6E15179990B

Answer 1

Row_number()，最后取2个，第一个取

select top(1) with ties *
from (
   select *, row_number() over(partition by IdentifierBySet order by IndexBySet desc) rn
   from @tbl ) t
where rn <=2
order by row_number() over(partition by IdentifierBySet order by rn desc)

通过索引 and/or ID 有条件地加入 table

Joining to a table conditionally by Index and/or ID

sql

tsql

sql-server-2012