对查询结果进行分组取top n

sql语句如下

;WITH t AS (
SELECT  *, ROW_NUMBER() over(partition by userid order by userid) as rownum FROM tableName
)
SELECT * FROM t WHERE t.rownum<@count

语句中通过partition by userid order by userid对查询的信息进行分组后，再通过rownum<@count来实现取分组后各项的top @count