SQL Exercise: Find the number of self-goals scored in EURO cup 2016

Last update on January 13 2026 12:20:17 (UTC/GMT +8 hours)

7. From the following table, write a SQL query to find the number of self-goals scored during the 2016 European Championship.

Sample table: goal_details

 goal_id | match_no | player_id | team_id | goal_time | goal_type | play_stage | goal_schedule | goal_half
---------+----------+-----------+---------+-----------+-----------+------------+---------------+-----------
       1 |        1 |    160159 |    1207 |        57 | N         | G          | NT            |         2
       2 |        1 |    160368 |    1216 |        65 | P         | G          | NT            |         2
       3 |        1 |    160154 |    1207 |        89 | N         | G          | NT            |         2
       4 |        2 |    160470 |    1221 |         5 | N         | G          | NT            |         1
       5 |        3 |    160547 |    1224 |        10 | N         | G          | NT            |         1
       6 |        3 |    160403 |    1218 |        61 | N         | G          | NT            |         2
       7 |        3 |    160550 |    1224 |        81 | N         | G          | NT            |         2
       8 |        4 |    160128 |    1206 |        73 | N         | G          | NT            |         2
       9 |        4 |    160373 |    1217 |        93 | N         | G          | ST            |         2
.........
     108 |       51 |    160319 |    1214 |       109 | N         | F          | ET            |         2

View the table

Sample Solution:

-- This SQL query calculates the count of rows in the 'goal_details' table where the 'goal_type' column has the value 'O'.

SELECT COUNT(*) 
-- COUNT(*) is an aggregate function that counts the number of rows in a result set.
FROM goal_details 
-- 'goal_details' is the name of the table being queried.
WHERE goal_type='O';
-- The WHERE clause filters rows where the 'goal_type' column has the value 'O'.

Sample Output:

 count
-------
     3
(1 row)

Code Explanation:

The said query in SQL that selects the number of rows in the goal_details table where the goal_type column is equal to 'O'.
The result of the query will be a single value representing the count of rows where goal_type is equal to 'O'.

Relational Algebra Expression: