Question

我在SQL Server中有一个视图，该视图为我提供了一些游戏的记录。它返回多个属于一个游戏的记录，它们具有相同的Gid，但不同的版本具有不同的Vids，如下所示

vid gid otherData(Platform)
2   1   PC
2   1   PC ...
3   1   X1
3   1   X2....
2   5   PC
2   5   PC ...
3   5   X1
3   5   X2....

如何使用分组依据并选择或仅通过其他方式选择这些记录？

3   1   X1
3   1   X2....
3   5   X1
3   5   X2....

Answer 1

您想要dense_rank()：

select top (1) with ties t.*
from table t
order by dense_rank() over (partition by gid order by vid desc);

编辑：

select t.*
from (select t.*,
             dense_rank() over (partition by gid order by vid desc) as seq
      from table t
     ) t
where seq = 1;

Answer 2

使用GROUP BY的解决方案：

使用CTE：

;WITH HighestVIDByGID AS
(
    SELECT
        V.gid,
        MaxVid = MAX(V.vid)
    FROM
        vYourView AS V
    GROUP BY
        V.gid
)
SELECT
    V.*
FROM
    vYourView AS V
    INNER JOIN HighestVIDByGID AS M ON 
        V.gid = M.gid AND
        V.vid = M.MaxVid

将INNER JOIN与子查询一起使用：

SELECT
    T.*
FROM
    vYourView AS T
    INNER JOIN (
            SELECT
                V.gid,
                MaxVid = MAX(V.vid)
            FROM
                vYourView AS V
            GROUP BY
                V.gid
        ) AS M ON
            T.gid = M.gid AND
            T.vid = M.MaxVid

使用EXISTS：

SELECT
    T.*
FROM
    vYourView AS T
WHERE
    EXISTS (
        SELECT
            'max vid version'
        FROM
            vYourView AS V
        GROUP BY
            V.gid
        HAVING
            T.gid = V.gid AND
            T.vid = MAX(V.vid))

如何在具有多个VID和其他字段的表中仅选择具有最大VID的行？

2 个答案: