sql-server – 在条件上过滤重复行

2023年4月26日 208次阅读

我想在条件上过滤重复的行,以便选择具有最小修改和最大活动和唯一rid和did的行.自我加入？或者任何更好的方法会更好地表现？

例：

id        rid                  modified                 active         did
1             1             2010-09-07 11:37:44.850              1             1
2             1             2010-09-07 11:38:44.000              1             1
3             1             2010-09-07 11:39:44.000              1             1
4             1             2010-09-07 11:40:44.000              0             1
5             2             2010-09-07 11:41:44.000              1             1
6             1             2010-09-07 11:42:44.000              1             2

预计产量为

1             1             2010-09-07 11:37:44.850              1             1
5             2             2010-09-07 11:41:44.000              1             1
6             1             2010-09-07 11:42:44.000              1             2

在评论第一个答案时,该建议不适用于以下数据集(当active = 0且modified是该行的最小值时)

 id        rid                     modified                      active           did
    1             1             2010-09-07 11:37:44.850              1             1
    2             1             2010-09-07 11:38:44.000              1             1
    3             1             2010-09-07 11:39:44.000              1             1
    4             1             2010-09-07 11:36:44.000              0             1
    5             2             2010-09-07 11:41:44.000              1             1
    6             1             2010-09-07 11:42:44.000              1             2

最佳答案 假设SQL Server 2005.如果要返回关联,请使用RANK()而不是ROW_NUMBER().

;WITH YourTable as
(
SELECT 1 id,1 rid,cast('2010-09-07 11:37:44.850' as datetime) modified, 1 active,1 did union all
SELECT 2,1,'2010-09-07 11:38:44.000', 1,1 union all
SELECT 3,1,'2010-09-07 11:39:44.000', 1,1 union all
SELECT 4,1,'2010-09-07 11:36:44.000', 0,1 union all
SELECT 5,2,'2010-09-07 11:41:44.000', 1,1 union all
SELECT 6,1,'2010-09-07 11:42:44.000', 1,2
),cte as
(
SELECT id,rid,modified,active, did,
ROW_NUMBER() OVER (PARTITION BY rid,did ORDER BY active DESC, modified ASC ) RN
FROM YourTable
)
SELECT id,rid,modified,active, did
FROM cte
WHERE rn=1
order by id
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