嗨我有一个包含J1,J2,J3,J4,J5,J6,J7列的表格.我想从这些列中找到最大的3个值为L1,L2,L3.
我尝试了下面的查询来找到第一个最大的
SELECT ( SELECT Max(v) FROM ( VALUES ([J1]),([J2]),([J3]),([J4]),([J5]),([J6]),([J7]) ) AS value(v) ) as [L1]FROM dbo.JTable
解决方法
如果您的表有PK,比如说id,那么您可以使用员工
UNPIVOT
的查询:
SELECT * FROM ( SELECT *,ROW_NUMBER() OVER (PARTITION BY id ORDER BY Val) AS rn FROM JTable UNPIVOT ( Val FOR Col IN (J1,J7)) AS unpvt) AS t WHERE t.rn <= 3
如果你想要每个id一行,那么你可以使用PIVOT撤消UNPIVOT操作:
SELECT id,[1],[2],[3] FROM ( SELECT id,Val,rn FROM ( SELECT id,Col,ROW_NUMBER() OVER (PARTITION BY id ORDER BY Val) AS rn FROM JTable UNPIVOT ( Val FOR Col IN (J1,J7)) AS unpvt) AS t WHERE t.rn <= 3) AS src PIVOT ( MAX(Val) FOR rn IN ([1],[3])) AS pvt
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