SQL Server 分組排序后取第N條數據（或前N條）

記錄一個分組取前N條數據的SQL:

SELECT  *
FROM    ( SELECT    ROW_NUMBER() OVER ( PARTITION  BY t1.X ORDER BY t1.Y ) AS RNUM ,
                    *
          FROM      Table1 t1
        ) AS T
WHERE   T.RNUM = N

X:分組的字段；

Y:排序的字段；

N:第N條