SQL Exercise: Captains of the top four teams in the semifinals

SQL soccer Database: Joins Exercise-31 with Solution

31. From the following tables, write a SQL query to find the captains of the top four teams that competed in the semi-finals (matches 48 and 49) of the tournament. Return country name, player name, jersey number and position to play.

Sample table: soccer_country

Sample table: match_captain

Sample table: player_mast

Sample Solution:

SQL Code:

SELECT country_name, player_name, jersey_no, posi_to_play 
FROM match_captain a
JOIN soccer_country b ON a.team_id=b.country_id
JOIN player_mast c ON a.player_captain=c.player_id
WHERE match_no IN(48,49);

Sample Output:

 country_name |    player_name     | jersey_no | posi_to_play
--------------+--------------------+-----------+--------------
 France       | Hugo Lloris        |         1 | GK
 Iceland      | Aron Gunnarsson    |        17 | MF
 Portugal     | Cristiano Ronaldo  |         7 | FD
 Wales        | Ashley Williams    |         6 | DF
(4 rows)

Code Explanation:

The said query in SQL that retrieves the captain's name, jersey number, position to play, and country name for the teams that played in the matches with match numbers 48 and 49.
The JOIN keyword joins the 'match_captain' and the 'soccer_country' tables based on the "team_id" and the "country_id" columns and another joins with the 'player_mast' and the 'match_captain' tables based on the "player_id" and the "player_captain" columns from the respective tables.
The WHERE clause in this query filters the teams that played in the matches with match numbers 48 and 49.

Relational Algebra Expression:

Relational Algebra Tree:

Practice Online

Sample Database: soccer

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Previous SQL Exercise: Find the final four teams in the tournament.
Next SQL Exercise: Find captains for all the matches in the tournament.