php mysql按多列选择顺序

Question

I have a problem . I want arrange order decrease of column. iphone4 ,iphone5, iphone6. For example:

Name |iphone4 |iphone5|iphone6 
john | 6      | 7     | 8      
Smith| 6      | 9     | 8      
Louis| 6      | 7     | 10      
Nick | 7      | 7     | 8      
john | 2      | 7     | 4 
Smith| 7      | 7     | 5

this is my mysql

Select Name, SUM(iphone4) ,SUM(iphone5),SUM(iphone6) from orders group by Name order by iphone4  DESC, iphone5 DESC, iphone6  DESC

but it's only working column iphone4 and iphone5. the rest, iphone6 it's don't working Who can help me?

Answer 1

The order would seem to not be working if the values were stored as strings instead of numbers.

If this is the case, then converting them to numbers fixes the problem:

Select m.*
from mark m
order by (mathematics + 0) DESC, (physics + 0) DESC, (chemistry + 0) DESC;

In addition, no GROUP BY seems to be needed for this query.

EDIT:

For the edited version, you need the aggregations in the order by as well as the select. To be explicit, I would write these as:

Select Name, SUM(iphone4+0), SUM(iphone5+0), SUM(iphone6+0)
from orders
group by Name
order by SUM(iphone4+0) desc, SUM(iphone5+0) desc, SUM(iphone6+0) desc;