Sql query for the lowest score per country - sql

Question

I have a database with 3 tables. In table country I have id and name columns. The sport table also has id and name columns. Finally, the table match has id, player1, and player2(that are ids of country that play one against other), winner_id (id of country that won the match) and sport_id of the sport which was played. The least wins means that I just need in which sport country had the least wins, no matther on played matches.
I want to show the sport per country with the least wins. It should look like this:
Country
Sport
Wins
France
Basketball
2
How can I construct this query? I'm using SQL Server.
Data in table look like this. Table countries:
country_id
name
1
France
2
England
Table sport:
sport_id
name
1
Footbal
2
Basketball
Table match:
match_id
player1
player2
winner_id
sport_id
1
3
1
3
1
2
6
4
4
2

Answer 1

I want to note that the used wording with least wins is not clear, in my solution with least wins means most matches played with least wins.
To get this ranking, we need to know how many matches a country has played in each sport and how many of those have been won.
SELECT
country.name AS country,
sport.name AS sport,
sport_wins.wins
FROM
country
OUTER APPLY (
SELECT TOP 1
t.match_count,
COALESCE(t.wins, 0) AS wins,
t.sport_id
FROM (
SELECT
COUNT(*) AS match_count,
m_c.sport_id,
t.wins
FROM match m_c
OUTER APPLY (
SELECT
COUNT(*) AS wins,
match.sport_id
FROM match
WHERE country.country_id = match.winner_id
AND match.sport_id = m_c.sport_id
GROUP BY match.sport_id
) t
WHERE country.country_id IN (m_c.player1, m_c.player2)
GROUP BY m_c.sport_id, t.wins
) t
ORDER BY t.wins ASC, t.match_count DESC
) sport_wins
JOIN sport ON sport.sport_id = sport_wins.sport_id
Please, check a demo.
If you do not take into account losses, but only the number of wins is of interest, you can use a query like this one
WITH cte AS (
SELECT
country.country_id,
sport.sport_id,
SUM(CASE WHEN match.winner_id = country.country_id THEN 1 ELSE 0 END) AS wins
FROM country
CROSS JOIN sport
JOIN match ON match.sport_id = sport.sport_id
AND country.country_id IN (match.player1, match.player2)
GROUP BY country.country_id, sport.sport_id
)
SELECT
country.name,
sport.name,
t.min_wins AS wins
FROM (
SELECT
country_id,
MIN(wins) AS min_wins
FROM cte
GROUP BY country_id
) t
JOIN cte ON cte.country_id = t.country_id AND cte.wins = min_wins
JOIN country ON cte.country_id = country.country_id
JOIN sport ON cte.sport_id = sport.sport_id
This query takes into account the fact that the country participates in matches in sport, so if a country does not compete in a sport, that sport will not be included in the statistics as it will have 0 wins and this will be the minimum value.
Please, check a demo

Answer 2

You need to first cross-join the sports with the countries, then get the total.
Then you can use a row-number approach to get the bottom country in each sport
SELECT
c.Country,
c.Sport,
c.Wins
FROM (
SELECT
c.name Country,
s.name Sport,
COUNT(m.winner_id) Wins,
ROW_NUMBER() OVER (PARTITION BY s.sport_id, s.name ORDER BY COUNT(m.winner_id)) rn
FROM country c
CROSS JOIN sport s
LEFT JOIN [match] m
ON s.sport_id = m.sport_id AND m.winner_id = c.country_id
GROUP BY
s.sport_id,
s.name,
c.country_id,
c.name
) c
WHERE c.rn = 1;