Selecting sum of single column depending on two columns on same table - mysql

Question

I have a table very similar to the one below. p1 and p2 on the table refer to id of player on an another table.
id score p1 p2 date
-- ----- -- -- ----
1 12 1 2 2011.10.21
2 23 3 4 2011.10.22
3 21 1 3 2011.10.23
4 35 5 1 2011.10.24
5 11 2 3 2011.10.25
What I want to do is the get the player id (p1 or p2) with highest score. My solution is something like select sum(score) but I can't form a query because a player may appear in both p1 or p2 columns.
Also a bigger problem is when I want to sort scores from highest to lowest. I dont know what to do. How can I sum and sort a score if I need to group to separate columns? The result I want is similar to this output:
pID score times_played
--- ----- ------------
1 68 3
3 55 3
5 35 1
2 23 2
4 23 1
Is my database design flawed? If there is a more intelligent way I'd like to know. Should I need seperate single queries so I can merge them on PHP or something?
Any help would be appreciated.
Cheers.
PS: I couldnt think a nice subject. Feel free to edit.

Answer 1

You can put the players in one column as so:
select id, score, p1 as player, date from yourtable
union all
select id, score, p2 as player, date from yourtable
You now have players in one column. You can do this to get the score sum for all players
select sum(score), player from (
select id, score, p1 as player, date from yourtable
union all
select id, score, p2 as player, date from yourtable
) group by player
Now, you say that you also want to know how many times the player played and sort them in descending order:
select sum(score), player, count(*) as timesPlayed from (
select id, score, p1 as player, date from yourtable
union all
select id, score, p2 as player, date from yourtable
) group by player order by sum(score) desc

Answer 2

Try this to get players with highest score (disregarding ties)
select id,p1,p2
from table t1
join (select max(score) as MaxS) xx on xx.MaxS = t1.Score
limit 1
To get player total score, try this
select Player as pID,Sum(tot) as Score, count(*) as TimesPlayed
from
(
select p1 as Player,sum(score) as Tot
from table
group by p1
union all
select p2,sum(score)
from table
group by p2
) xx
Group by xx.Player
order by Score desc

Answer 3

Alternatively to using UNION (ALL) on the table, you could try something like this:
SELECT
CASE p.PlayerNumber WHEN 1 THEN t.p1 ELSE t.p2 END AS pID,
SUM(t.score) AS score,
COUNT(*) AS times_played
FROM atable t
CROSS JOIN (SELECT 1 AS PlayerNumber UNION ALL SELECT 2) p
GROUP BY
pID /* this is probably MySQL-specific; most, if not all, other major
database systems would require repeating the entire pID expression here, i.e.
GROUP BY
CASE p.PlayerNumber WHEN 1 THEN t.p1 ELSE t.p2 END
*/
ORDER BY
score DESC,
times_played DESC /* this is based on your result set;
you might want to omit it or change it to ASC */
UPDATE, in an answer to a question in the comments: joining the result set to the user table:
SELECT
`user`.*, /* you should probably specify
the necessary columns explicitly */
totals.score,
totals.times_played
FROM `user` u
INNER JOIN (
SELECT
CASE p.PlayerNumber WHEN 1 THEN t.p1 ELSE t.p2 END AS pID,
SUM(t.score) AS score,
COUNT(*) AS times_played
FROM atable t
CROSS JOIN (SELECT 1 AS PlayerNumber UNION ALL SELECT 2) p
GROUP BY
pID
) totals ON user.id = totals.pID
ORDER BY
totals.score DESC,
totals.times_played DESC