如果列值与先前行不同,请选择行

Question

我有一张如下表

No. FName Age  Tag
1    abc   22    c
2    xyz   60    c
3    pqr   62    i
4    abc   22    i
5    abc   32    i

我希望结果返回为

No. FName Age  Tag
1    abc   22    c
2    xyz   60    c
3    pqr   62    i
5    abc   32    i

要求是,如果一列Name 与列Age值相同的行用tag=c and tag=i,比tag=i排应该不会被选中.

排号 1和行号.4具有相同的值(Name,age)=(abc,22)但行4具有tag = i.
因此(abc,22,i),必须排除上面的第4行.我怎样才能做到这一点 ？

Answer 1

WITH records
AS
(
    SELECT  No, FName, Age, Tag,
            ROW_NUMBER() OVER (PARTITION BY FName, Age
                                ORDER BY Tag ASC) rn
    FROM    tableName
    WHERE   TAG IN ('c','i')
)
SELECT  No, FName, Age, Tag
FROM    records
WHERE   rn = 1

• SQLFiddle演示

如果您有其他特殊值TAG,

WITH records
AS
(
    SELECT  No, FName, Age, Tag,
            ROW_NUMBER() OVER (PARTITION BY FName, Age
                                ORDER BY CASE WHEN TAG = 'c' THEN 0 ELSE 1 END ASC) rn
    FROM    tableName
    WHERE   TAG IN ('c','i')
)
SELECT  No, FName, Age, Tag
FROM    records
WHERE   rn = 1
ORDER   BY No

• SQLFiddle演示

更新1

SELECT Fname, Age, MIN(tag) Tag
FROM   TableName
WHERE  TAG IN ('c','i')
GROUP  BY Fname, Age

• SQLFiddle演示