Display data from multiple tables in Oracle in one line - sql

Question

I have got 3 tables as follows:
table_teams (id_team, name, city)
table_matches (id_match, date_of_match, city)
table_game (id, id_team (FK), id_match (FK), goals) -- this one is a junction table between the first two
The same match is introduced into table_game as two separate records, one for each team with its number of goals, but having the same id_match,
INSERT INTO table_game(id_team, id_match, goals) VALUES('GER', 1234, 7);
INSERT INTO table_game(id_team, id_match, goals) VALUES('BRA', 1234, 1);
and as a single record into table_matches,
INSERT INTO table_matches(id_match, date_of_match, city)
VALUES (1234, '8-JUL-2014', 'Belo Horizonte');
Now, I would like to create a view that selects data from these tables and displays it as follows:
Date | Team1 | Goals1 | Goals2 | Team2 | City
The best I managed to do so far is display each record on separate lines in the table.
SELECT tm.date_of_match, tt.name, tg.goals, tm.city
FROM table_matches tm, table_teams tt, table_game tg
WHERE tm.id_match = tg.id_match AND tt.id_team = tg.id_team;
But I have no idea how to display data as stated above. All my tries resulted in a big mess.
Will appreciate some help. Thank you.

Answer 1

Using JOIN syntax
-- Test data
WITH table_game(ID, id_team, id_match, goals) AS (
SELECT 10, 'USA', 100, 5 FROM dual UNION ALL -- error (3 records for same match)
SELECT 11, 'RUS', 100, 4 FROM dual UNION ALL -- error (3 records for same match)
SELECT 12, 'BRA', 100, 3 FROM dual UNION ALL -- error (3 records for same match)
SELECT 20, 'ARG', 1234, 7 FROM dual UNION ALL
SELECT 21, 'BRA', 1234, 1 FROM dual UNION ALL
SELECT 30, 'ENG', 4321, 6 FROM dual UNION ALL
SELECT 31, 'FRA', 4321, 2 FROM dual
)
,table_matches(id_match, date_of_match, city) AS (
SELECT 1234, DATE '2014-07-08', 'Belo Horizonte' FROM dual UNION ALL
SELECT 4321, DATE '2014-08-09', 'Sao Paulo' FROM dual UNION ALL
SELECT 100, DATE '2014-09-10', 'Brasilia' FROM dual)
,table_teams(id_team, NAME, city) AS (
SELECT 'ARG', 'Argentina', 'Buenos Aires' FROM dual UNION ALL
SELECT 'BRA', 'Brazil', 'Sao Paulo' FROM dual UNION ALL
SELECT 'ENG', 'England', 'London' FROM dual UNION ALL
SELECT 'FRA', 'France', 'Paris' FROM dual UNION ALL
SELECT 'RUS', 'Russia', 'Moscow' FROM dual UNION ALL
SELECT 'USA', 'United States', 'New York' FROM dual)
-- End Test data
,match_teams AS (
SELECT id_match, MAX(id_team) team1, MIN(id_team) team2
FROM table_game
GROUP BY id_match
HAVING COUNT(*) = 2 -- any valid match should have only 2 teams, otherwise ignored
)
SELECT M.date_of_match, t1.NAME team1, g1.goals goals1, t2.NAME team2, g2.goals goals2, M.city city_match
FROM table_matches M
JOIN match_teams mt ON mt.id_match = M.id_match
JOIN table_game g1 ON g1.id_match = M.id_match AND g1.id_team = mt.team1
JOIN table_game g2 ON g2.id_match = M.id_match AND g2.id_team = mt.team2
JOIN table_teams t1 ON t1.id_team = mt.team1
JOIN table_teams t2 ON t2.id_team = mt.team2
/
Joins on WHERE clause
-- Test data
WITH table_game(ID, id_team, id_match, goals) AS (
SELECT 10, 'USA', 100, 5 FROM dual UNION ALL -- error (3 records for same match)
SELECT 11, 'RUS', 100, 4 FROM dual UNION ALL -- error (3 records for same match)
SELECT 12, 'BRA', 100, 3 FROM dual UNION ALL -- error (3 records for same match)
SELECT 20, 'ARG', 1234, 7 FROM dual UNION ALL
SELECT 21, 'BRA', 1234, 1 FROM dual UNION ALL
SELECT 30, 'ENG', 4321, 6 FROM dual UNION ALL
SELECT 31, 'FRA', 4321, 2 FROM dual
)
,table_matches(id_match, date_of_match, city) AS (
SELECT 1234, DATE '2014-07-08', 'Belo Horizonte' FROM dual UNION ALL
SELECT 4321, DATE '2014-08-09', 'Sao Paulo' FROM dual UNION ALL
SELECT 100, DATE '2014-09-10', 'Brasilia' FROM dual)
,table_teams(id_team, NAME, city) AS (
SELECT 'ARG', 'Argentina', 'Buenos Aires' FROM dual UNION ALL
SELECT 'BRA', 'Brazil', 'Sao Paulo' FROM dual UNION ALL
SELECT 'ENG', 'England', 'London' FROM dual UNION ALL
SELECT 'FRA', 'France', 'Paris' FROM dual UNION ALL
SELECT 'RUS', 'Russia', 'Moscow' FROM dual UNION ALL
SELECT 'USA', 'United States', 'New York' FROM dual)
-- End Test data
,match_teams AS (
SELECT id_match, MAX(id_team) team1, MIN(id_team) team2
FROM table_game
GROUP BY id_match
HAVING COUNT(*) = 2 -- any valid match should have only 2 teams, otherwise ignored
)
SELECT M.date_of_match, t1.NAME team1, g1.goals goals1, t2.NAME team2, g2.goals goals2, M.city city_match
FROM table_matches M
,match_teams mt
,table_game g1
,table_game g2
,table_teams t1
,table_teams t2
WHERE mt.id_match = M.id_match
AND g1.id_match = M.id_match
AND g1.id_team = mt.team1
AND g2.id_match = M.id_match
AND g2.id_team = mt.team2
AND t1.id_team = mt.team1
AND t2.id_team = mt.team2
/

Answer 2

you can use ROW_NUMBER to assign a value then join against it, something like this:
;with cte (team,match,goals,row) as
(
select
id_team,
id_match,
goals,
ROW_NUMBER () over (partition by match_id order by team_id)
from table_game
)
select
t1.date_of_match,c.team, c.goals, c1.goals, c1.team, t1.city
from cte c
left join cte c1 on c.match = c1.match and c1.row = 2
inner join table_matches t1 on c.match = t1.id_match
where c.row = 1

Answer 3

select date_of_match, g1.id_team team1, g1.goals goals1,
g2.goals goals2, g2.id_team team2, m.city
from matches m
join games g1 on g1.id_match = m.id_match
join games g2 on g1.id_match = m.id_match and g2.id > g1.id
test:
with games(id, id_team, id_match, goals) as (
select 1, 'GER', 1234, 7 from dual union all
select 2, 'BRA', 1234, 1 from dual),
matches(id_match, date_of_match, city) as (
select 1234, date '2014-07-08', 'Belo Horizonte' from dual)
select date_of_match, g1.id_team team1, g1.goals goals1,
g2.goals goals2, g2.id_team team2, m.city
from matches m
join games g1 on g1.id_match = m.id_match
join games g2 on g1.id_match = m.id_match and g2.id > g1.id
result:
DATE_OF_MATCH TEAM1 GOALS1 GOALS2 ID_TEAM CITY
------------- ------- ------ ------ ------- --------------------
2014-07-08 GER 7 1 BRA Belo Horizonte