如何计算等于相同ID的所有行中的列？

Question

I have a table 3 table: users , res_info , reservations

I want to calculate the number of kilometers traveled by each driver in the trip from the highest kilometer to the lowest.

In field total_kms , I want to display the total kilometers per driver: for example Mohamed Mostafa Cutting distance 550 and 323 km

The following information will be displayed in the table:

name  ----------------   |    total kms    
mohamed mostafa          |     873

This my code i have tried :

select 
    users.name, count(res_info.res_id) as total_drives,
    (reservations.meters + reservations.meters) as   total_kms,
    reservations.meters as kms 
from 
    reservations 
    left outer join res_info 
        on (reservations.id=res_info.res_id) 
    left outer join users on (reservations.driver_id=users.id) 
where 
    reservations.zone_id = 2 
    and reservations.meters !='' 
group by 
    res_info.res_id 
order by 
    count(res_info.res_id) desc

Answer 1

You don't need reservations.meters as kms anymore because it's breaking the grouping on the SUM. And you need to order by SUM instead of count since you want to order by most distance traveled by driver. Here is what you need :

select 
    users.name, count(res_info.res_id) as total_drives,
    sum(reservations.meters + reservations.meters) as total_kms
from 
    reservations 
    left outer join res_info 
        on (reservations.id=res_info.res_id) 
    left outer join users on (reservations.driver_id=users.id) 
where 
    reservations.zone_id = 2 
    and reservations.meters !='' 
group by 
    users.name 
order by 
    total_kms desc