使用分区在mysql中排序顺序/十进制

Question

我的数据集中有多组城市，我正在尝试为mysql中的每个组排序。有人可以帮我转换分区子句到mysql吗？

Answer 1

我假设你正在寻找相当于rank() over (partition by city order by price)的东西。您可以使用子查询执行此操作：

select d.*,
       (select 1 + count(price)
        from dataset d2
        where d2.city = d.city and d2.price < d.price
       ) as rank
from dataset d;

或使用变量：

select d.*,
       (@rn := if(@city = city and @price > price, if(@price = @price, @rn + 1, @rn + 1),
                  if(@city = city and @price = price, @rn,
                     if(@city := city, if(@price := price, 1, 1), 1)
                    )
                 )
       ) as rank                  
from dataset d cross join
     (select @rn := 0, @city := '', @price = -1)
order by city, price;