Multiple aggregate count columns SQL - mysql

Question

I have a table that roughly looks like the following:
winner_name
loser_name
Person A
Person B
Person A
Person C
Person B
Person A
Person C
Person B
I'm trying to return a table that looks like the following:
player_name
number_wins
number_losses
Person A
2
1
Person B
1
2
Person C
1
1
I can't quite figure out how to get there. I have been able to write a query that returns player_name and either number_wins or number_losses, but not both.
SELECT winner_name AS player_name, COUNT(*) AS number_wins
FROM my_table
GROUP BY player_name
I have looked into using procedures, functions, and subqueries to do this but I haven't found the right solution yet. Any direction would be helpful.

Answer 1

You need to pivot the names into the same column using UNION. Then you can calculate the sum of wins and losses.
SELECT player_name, SUM(win) AS number_wins, SUM(loss) AS number_losses)
FROM (
SELECT winner_name AS player_name, 1 AS win, 0 AS loss
FROM my_table
UNION ALL
SELECT loser_name AS player_name, 0 AS win, 1 AS loss
FROM my_table
) AS x
GROUP BY player_name

Answer 2

Since each aggregate statistic is for a different group (one for winner_name, the other for loser_name), they can't be calculated in the same query, but each query can be run separately and then combined with a JOIN. Simply take each query:
SELECT winner_name AS player, COUNT(loser_name) AS wins
FROM games
GROUP BY winner_name
;
SELECT loser_name AS player, COUNT(winner) AS losses
FROM games
GROUP BY loser_name
;
and join on the common attribute, the player name:
SELECT gw.player, gw.wins, gl.losses
FROM (
SELECT winner_name AS player, COUNT(loser_name) AS wins
FROM games
GROUP BY winner_name
) AS gw
JOIN (
SELECT loser_name AS player, COUNT(winner_name) AS losses
FROM games
GROUP BY loser_name
) AS gl
ON gl.player = gw.player
;
Whether using unions or joins, each distinct group that is the basis for aggregate statistics will require a separate sub-select.