Question

在此示例中，我是否可以使用T-SQL语法和单个select语句仅检索行BB，DD和FF？

C1 | C2 | C3 | C4
-----------------
AA | KK | 11 | 99
BB | KK | 11 | 99   
CC | KK | 22 | 99
DD | KK | 22 | 99
EE | KK | 33 | 99
FF | KK | 33 | 99

好的，所以我最终解决了我的问题：SELECT distinct [C4]，[C1]，[C2]，[C3] FROM [Table]其中[C4] ='MyValue'顺序由[ C3] desc。

Answer 1

试一试：

SELECT C1, C2, C3, C4 FROM mytable WHERE C1 IN ('BB', 'DD', 'FF')

如果要使C3列唯一，则查询应为：

SELECT MAX(C1), C2, C3, C4 FROM mytable GROUP BY C2, C3, C4

Answer 2

试试这个

SELECT t.C1, t.C2, t.C3, t.C4 FROM 
(
    SELECT *,
             ROW_NUMBER() OVER (PARTITION BY C3 ORDER BY C1 DESC) AS seqnum
    FROM MyTable
) t
WHERE seqnum = 1

Answer 3

这适用于您的特定示例：

SELECT
  C1 = MAX(C1),
  C2,
  C3,
  C4
FROM atable
GROUP BY
  C2,
  C3,
  C4
;

如果从C1中选择正确的值，则应遵循比获取MAX()更复杂的逻辑，您可能需要使用@bvr's suggestion（调整ORDER BY正确地说。）

SQL Server：不确定如何检索选定的记录

3 个答案: