Oracle 取Group By 第一條

select 查詢内容 from

(

  select row_number() over(partition by 分組字段 order by 排序字段) as rn , 查詢字a,查詢字段b..

     from  表1,表2 where 條件

) where rn = 1 ;

select 查詢内容 from

(

  select row_number() over(partition by 分組字段 order by 排序字段) as xuhao , 查詢字a,查詢字段b..

     from  表1 left join 表2 on 條件

) where xuhao = 1