Getting sum of 2 columns each with unique condition - sql

Question

I've two tables like this.
create table teams (
"ID" Integer NOT NULL ,
"STADIUM_ID" Integer NOT NULL ,
"NAME" Varchar2 (50) NOT NULL ,
primary key ("ID")
) ;
create table matches (
"ID" Integer NOT NULL ,
"WINNER_ID" Integer NOT NULL ,
"OPPONENT_ID" Integer NOT NULL ,
"WINNERSCORE" Integer,
"OPPONENTSCORE" Integer,
primary key ("ID","WINNER_ID","OPPONENT_ID")
) ;
They have the following data :
select * from matches;
ID WINNER_ID OPPONENT_ID WINNERSCORE OPPONENTSCORE
---------- ---------- ----------- ----------- -------------
1 5 2 5 2
2 4 5 1 0
3 3 2 1 0
4 3 2 1 0
5 1 2 2 0
6 3 1 2 1
select * from teams;
ID STADIUM_ID NAME
---------- ---------- -----------
1 1 Team1
2 3 Team2
3 4 Team3
4 2 Team4
5 5 Team5
I need to get the sum of the goals for each team.
For this aim, tried the following query and got the results below :
select name,
(select sum(opponentscore)
from matches
where opponent_id = teams.id) +
(select sum(winnerscore) from matches where winner_id = teams.id) sum
from teams;
NAME SUM
-------------------------------------------------- ----------
Team1 3
Team2
Team3
Team4
Team5 5
Do you have any suggestion ?

Answer 1

All you need is to calculate seperately opponentscore and winnerscore by each individual team, and combine them with UNION ALL :
select name, sum(score) total_score
from
(
select name, sum(winnerscore) score
from teams t join matches m on ( t.id = m.winner_id )
group by name
union all
select name, sum(opponentscore) score
from teams t join matches m on ( t.id = m.opponent_id )
group by name
)
group by name
order by 1;
SQL Fiddle Demo

Answer 2

you should use join and group by
select name, sum(matches.opponentscore) + sum(matches.winnerscore) my_sum
from matches
inner join teams on teams.id = matches.winner_id
group by teams.name

Answer 3

You could join table teams twice with table matches:
SELECT name, SUM(wonMatches.WINNERSCORE + lostMatches.OPPONENTSCORE) as goals
FROM (teams INNER JOIN matches as wonMatches ON teams.ID = wonMatches.WINNER_ID)
INNER JOIN matches as lostMatches ON teams.ID = lostMatches.OPPONENT_ID
GROUP BY name

Answer 4

My solution is : change your database schema. Restart thinking your app's requirements. This schema does not answer the value your user are expecting from you.
From what I see, I would say that you're trying to build an app for fans that want to track their team / favorite player progress so they can brag.
That being said, I would have, at the end, those tables :
fan
team (id_team)
player (id_player, id_team)
tournament (id_tournament)
match (id_match, id_tournament, start_on, id_team_home, id_team_visitor)
goals (id_match, id_player, goaled_on)
So now, I believe that writing your query would be much more simple. You'll just have to join team, player, count over goals and group by team.

Answer 5

The problem is with NULLs - the subqueries return NULL when no result is found, and NULL + anything == NULL.
Most straightforward fix is:
select name,
nvl(
(select sum(opponentscore) from matches where opponent_id = teams.id),
0
)
+
nvl(
(select sum(winnerscore) from matches where winner_id = teams.id),
0
) sum
from teams;
For performance reasons tohugh, you might want to consider using a joined query with GROUP BY as suggested by others.