Question

So lets say i have 2 tables.

table users:

id | name | date

table weight_tracking;

id | user_id | previous_weight | current_weight | date

weight_tracking table is being updated daily with user current weight and previous_weight.

I am trying to display all users ordering by previous_weight – current_weight (so by the difference in weight – who ever lost the most weight will show up first)

Can that be done with 1 call ?

Answer 1

SELECT users.*, weight_tracking.*
FROM users left join weight_tracking on users.id = weight_tracking.user_id
ORDER BY previous_weight - current_weight desc

if a user can have more than one row in weight_tracking table, you could use something like this:

SELECT users.*
FROM users left join weight_tracking on users.id = weight_tracking.user_id
GROUP BY users.id
ORDER BY max(previous_weight) - min(current_weight) desc