MySQL INNER JOIN select only one row from second table

Question

I have a users table and a payments table, for each user, those of which have payments, may have multiple associated payments in the payments

Answer 1

   SELECT u.* 
        FROM users AS u
        INNER JOIN (
            SELECT p.*,
             @num := if(@id = user_id, @num + 1, 1) as row_number,
             @id := user_id as tmp
            FROM payments AS p,
                 (SELECT @num := 0) x,
                 (SELECT @id := 0) y
            ORDER BY p.user_id ASC, date DESC)
        ON (p.user_id = u.id) and (p.row_number=1)
        WHERE u.package = 1

Answer 2

SELECT u.*, p.*
FROM users AS u
INNER JOIN payments AS p ON p.id = (
    SELECT id
    FROM payments AS p2
    WHERE p2.user_id = u.id
    ORDER BY date DESC
    LIMIT 1
)

Or

SELECT u.*, p.*
FROM users AS u
INNER JOIN payments AS p ON p.user_id = u.id
WHERE NOT EXISTS (
    SELECT 1
    FROM payments AS p2
    WHERE
        p2.user_id = p.user_id AND
        (p2.date > p.date OR (p2.date = p.date AND p2.id > p.id))
)

This solutions are better than the accepted answer because they work correctly when there are multiple payments with same user and date. You can try on SQL Fiddle.

Answer 3

This is quite simple do The inner join and then group by user_id and use max aggregate function in payment_id assuming your table being user and payment query can be

select user.id, max(payment.id) from user inner join payment on (user.id = payment.user_id) group by user.id

Answer 4

@John Woo's answer helped me solve a similar problem. I've improved upon his answer by setting the correct ordering as well. This has worked for me:

SELECT  a.*, c.*
FROM users a 
    INNER JOIN payments c
        ON a.id = c.user_ID
    INNER JOIN (
        SELECT user_ID, MAX(date) as maxDate FROM
        (
            SELECT user_ID, date
            FROM payments
            ORDER BY date DESC
        ) d
        GROUP BY user_ID
    ) b ON c.user_ID = b.user_ID AND
           c.date = b.maxDate
WHERE a.package = 1

I'm not sure how efficient this is, though.

Answer 5

SELECT U.*, V.* FROM users AS U 
INNER JOIN (SELECT *
FROM payments
WHERE id IN (
SELECT MAX(id)
FROM payments
GROUP BY user_id
)) AS V ON U.id = V.user_id

This will get it working

Answer 6

Matei Mihai given a simple and efficient solution but it will not work until put a MAX(date) in SELECT part so this query will become:

SELECT u.*, p.*, max(date)
FROM payments p
JOIN users u ON u.id=p.user_id AND u.package = 1
GROUP BY u.id

And order by will not make any difference in grouping but it can order the final result provided by group by. I tried it and it worked for me.