My current MySQL join is not working - php

Question

I have the following tables:
Users
id | name
-----------------
1 | Johny Bravo
Orders
id | users_id | number
----------------------
1 | 1 | 111111
2 | 1 | 222222
3 | 1 | 333333
4 | 1 | 444444
Example
id | text | number
------------------
1 | test | 111111
2 | test | 111111
3 | test | 222222
4 | test | 222222
5 | test | 333333
6 | test | 333333
Desired Outcome
id: 1
name: Johny Brawo
count(orders): 4
count(example): 6
My current query, which doesn't work
SELECT users.id, users.name, count(orders.id), count(example.id)
FROM users
LEFT JOIN orders ON orders.users_id=users.id
LEFT JOIN example ON example.number=orders.number
GROUP BY users.id
My current result
id: 1
name: Johny Brawo
count(orders): 8
count(example): 8
Any help would be greatly appreciated.

Answer 1

try count(distinct orders.id), count(distinct example.id)
I've not done any MySQL really, but this works in other Databases...

Answer 2

Starting - a little bit of theory. What does your query do?
First it SELECTs something from users table.
Then it LEFT JOINs with orders table. Number of returned rows is a multiplication of rows from users table and matching rows from orders table. So with only this join you will have 6 rows, each one with Johny Bravo as user, but with different orders data.
Then - another LEFT JOIN. This time with example table. Again - a number of returned rows is a multiplication of rows from orders table and matching rows from example table. So without GROUP BY and COUNT you will have eight rows of result.
Now, the GROUP BY query part. What does it do? It just groups rows with matching GROUP BY column(s). So it will group all rows with same users.id. There are eight of them.
Standard COUNT() will return a number of rows with not null value. As there were eight rows, both counts will return 8.
Now, as #GPW suggested, the solution is a COUNT(DISTINCT x). This function returns a count of unique not null rows.
Thus, the query should look like:
SELECT users.id, users.name, count(DISTINCT orders.id), count(DISTINCT example.id)
FROM users
LEFT JOIN orders ON orders.users_id=users.id
LEFT JOIN example ON example.number=orders.number
GROUP BY users.id
UPDATE - ordering and strict databases
You have also asked about ordering the result. You can order it by any column from your query. As MySQL is not very strict when it comes to grouping, you will also be able to order by any column from users table, as users table results are unique (grouped by id). You can also add, for example ORDER BY COUNT(DISTINCT orders.id) DESC to find users with largest number of orders.
Most databases, though, is more strict in GROUP BY queries. It allows to SELECT only columns with aggregated values or those explicitly contained in GROUP BY clause. So your GROUP BY clause should rather look like
GROUP BY users.id, users.name