Question

I have three tables:

user(id, name);

tasks(id, user_id, text, date);

bonus(id, user_id, sum, date, type).

I’m trying to write a query that will give me a list of all users, quantity of their tasks and a sum of bonuses of every type, each in separate column.

There are three types of bonuses:

type = (1, 2, 3)

So, I mean a table, which looks like this

name | task_count | bonus_1 | bonus_2 | bonus_3

Answer 1

SELECT u.name, 
        t.task_count, 
        SUM(CASE WHEN b.type=1 then b.sum END) AS bonus_1,
        SUM(CASE WHEN b.type=2 then b.sum END) AS bonus_2,
        SUM(CASE WHEN b.type=3 then b.sum END) AS bonus_3
FROM user u 
LEFT JOIN (SELECT user_id, COUNT(*) AS task_count 
           FROM tasks 
           GROUP BY user_id) t ON t.user_id = u.id
LEFT JOIN bonus b ON b.user_id = u.id 
GROUP BY u.id,u.name,t.task_count