1：数据表

2：问题：查询各个部门的最低工资的userid号

select a.* from

(select ROW_NUMBER() over(partition by dept order by salary asc) rn,userid,salary,dept from salary ) a

where rn=1

3：分析

partition by dept 是对dept进行分组，、

order by salary  分组后按salary进行排序

select ROW_NUMBER() over(partition by dept order by salary asc) rn,userid,salary,dept from salary

sql2005 新加的函数 row_number ()