SQL subquery that returns more than one column

Question

I am trying to execute what I think is an easy SQL statement, but I am receiving an error when I try and use a subquery saying that more than one column is being returned, but I need more than one column to be returned.

I am just trying to show two columns, my user's name, and their current balance

Here is the SQL:

SELECT playid, username, balance FROM plays order by playid desc limit 25

Which returns:

Play ID Username    Balance

593     ken     -3497

592     cass    -204

591     cass    -184

590     cass    -164

589     ken     -517

580     ken     -837

579     sam      250

545     cass    -134

544     cass    -114

Which is exactly what I want. A list of all my members, and their balances. Now I need to run a SUBQUERY on this query, to only select the balance with the highest Id (The most recent balance) Which would return a table like this:

Play ID Username    Balance

593     ken     -3497

592     cass    -204

579     sam      250

The most recent balance is the only thing that I am concerned with. When I try and execute this second query, I get an error saying that I am trying to return multiple columns. (which I am of course)

Any help would be greatly appreciated.

Answer 1

EDIT: You've now mentioned this is for MySQL. Try this:

SELECT
    p1.playid,
    p1.username,
    p1.balance
FROM
    plays p1
JOIN
    (
    SELECT
        MAX(playid) AS playid,
        username
    FROM
        plays
    GROUP BY
        username
    ) p2
    ON  (p2.username = p1.username)
    AND (p2.playid = p1.playid);

- This is probably what you are looking for. I assume you want the most recent balance by username based on the play id:

SELECT
    playid,
    username,
    balance
FROM
    (
    SELECT
        playid,
        username,
        balance,
        ROW_NUMBER() OVER(PARTITION BY username ORDER BY playid DESC) AS seq
    FROM
        plays
    ) base
WHERE
    seq = 1

This sequences the records by username, on playid descending, then returns the most recent record for each.