SQL Exercise: Number of countries participated in the EURO cup 2016

Last update on January 13 2026 12:20:24 (UTC/GMT +8 hours)

2. From the following table, write a SQL query to count the number of countries that participated in the 2016-EURO Cup.

Sample table: player_mast

 player_id | team_id | jersey_no |       player_name       | posi_to_play | dt_of_bir  | age |    playing_club
-----------+---------+-----------+-------------------------+--------------+------------+-----+---------------------
    160001 |    1201 |         1 | Etrit Berisha           | GK           | 1989-03-10 |  27 | Lazio
    160008 |    1201 |         2 | Andi Lila               | DF           | 1986-02-12 |  30 | Giannina
    160016 |    1201 |         3 | Ermir Lenjani           | MF           | 1989-08-05 |  26 | Nantes
    160007 |    1201 |         4 | Elseid Hysaj            | DF           | 1994-02-20 |  22 | Napoli
    160013 |    1201 |         5 | Lorik Cana              | MF           | 1983-07-27 |  32 | Nantes
    160010 |    1201 |         6 | Frederic Veseli         | DF           | 1992-11-20 |  23 | Lugano
    160004 |    1201 |         7 | Ansi Agolli             | DF           | 1982-10-11 |  33 | Qarabag
    160012 |    1201 |         8 | Migjen Basha            | MF           | 1987-01-05 |  29 | Como
    160017 |    1201 |         9 | Ledian Memushaj         | MF           | 1986-12-17 |  29 | Pescara
......
    160548 |    1224 |        23 | Simon Church            | FD           | 1988-12-10 |  27 | MK Dons

View the table

Sample Solution:

-- This SQL query calculates the count of distinct 'team_id' values in the 'player_mast' table.
	
SELECT COUNT(DISTINCT team_id) 
-- COUNT(DISTINCT team_id) counts the number of unique 'team_id' values in the result set.
FROM player_mast;
-- 'player_mast' is the name of the table from which the distinct 'team_id' count is being calculated.

Sample Output:

 count
-------
    24
(1 row)

Code Explanation:

The said query in SQL that counts the number of distinct team_id values in the player_mast table. The result of the query will be a single value that represents the number of different teams that are represented in the player_mast table.
The DISTINCT keyword is used to eliminate duplicate values before counting. This means that if there are multiple records in the player_mast table with the same team_id, they will only be counted as one for the purpose of this query.

Relational Algebra Expression: