Question

I have three existing SQL tables we will call “teams”, “miles”, and “riders”. Leaving out the fluff, their structure looks like this:

Table: teams
------------+-------------+---------+
| team_name | captains_id | team_id |
------------+-------------+---------+
| superbads | 11          | 1       |
| superflys | 12          | 2       |
------------+-------------+---------+

Table: riders
--------------+-----------+----------+
| rider_name  | team_id   | rider_id |
--------------+-----------+----------+
| donatello   | 1         | 10       |
| leonardo    | 1         | 11       |
| michelangelo| 2         | 12       |
| raphael     | 2         | 13       |
--------------+-----------+----------+

Table: miles
--------------+-----------+----------+
| rider_id    | miles     | id       |
--------------+-----------+----------+
| 10          | 100       | 1        |
| 10          | 62        | 2        |
| 11          | 110       | 3        |
| 11          | 100       | 4        |
| 12          | 8         | 5        |
| 12          | 22        | 6        |
| 13          | 29        | 7        |
| 13          | 2         | 8        |
--------------+-----------+----------+

I need to return a list of teams with total miles generated by that team (I also need to return the team captain’s name, but that’s a bit easier).
The difficulty is that I need to join miles on riders, sum the “miles” field, and then join that on teams somehow.

Changing the table structure is pretty much out, as this is an existing application. This is a LAMP environment, so manipulating PHP arrays after the query is an option if needed.

Answer 1

This should do it:

select t.team_id, t.team_name, t.captains_id, sum(m.miles) as total_miles
from teams t
inner join riders r on r.team_id = t.team_id
inner join miles m on m.rider_id = r.rider_id
group by t.team_id, t.team_name, t.captains_id