SQL Exercise: Matches decided by penalties in the Round of 16

Last update on January 13 2026 12:20:28 (UTC/GMT +8 hours)

10. From the following table, write a SQL query to find number of matches decided by penalties in the Round 16.

Sample table: match_mast

 match_no | play_stage | play_date  | results | decided_by | goal_score | venue_id | referee_id | audence | plr_of_match | stop1_sec | stop2_sec
----------+------------+------------+---------+------------+------------+----------+------------+---------+--------------+-----------+-----------
        1 | G          | 2016-06-11 | WIN     | N          | 2-1        |    20008 |      70007 |   75113 |       160154 |       131 |       242
        2 | G          | 2016-06-11 | WIN     | N          | 0-1        |    20002 |      70012 |   33805 |       160476 |        61 |       182
        3 | G          | 2016-06-11 | WIN     | N          | 2-1        |    20001 |      70017 |   37831 |       160540 |        64 |       268
        4 | G          | 2016-06-12 | DRAW    | N          | 1-1        |    20005 |      70011 |   62343 |       160128 |         0 |       185
        5 | G          | 2016-06-12 | WIN     | N          | 0-1        |    20007 |      70006 |   43842 |       160084 |       125 |       325
        6 | G          | 2016-06-12 | WIN     | N          | 1-0        |    20006 |      70014 |   33742 |       160291 |         2 |       246
        7 | G          | 2016-06-13 | WIN     | N          | 2-0        |    20003 |      70002 |   43035 |       160176 |        89 |       188
        8 | G          | 2016-06-13 | WIN     | N          | 1-0        |    20010 |      70009 |   29400 |       160429 |       360 |       182
        9 | G          | 2016-06-13 | DRAW    | N          | 1-1        |    20008 |      70010 |   73419 |       160335 |        67 |       194
.........
       51 | F          | 2016-07-11 | WIN     | N          | 1-0        |    20008 |      70005 |   75868 |       160307 |       161 |       181

View the table

Sample Solution:

-- This SQL query calculates the count of rows in the 'match_mast' table where the 'decided_by' column has the value 'P'
-- and the 'play_stage' column has the value 'R'.

SELECT COUNT(*) 
-- COUNT(*) is an aggregate function that counts the number of rows in a result set.
FROM match_mast 
-- 'match_mast' is the name of the table being queried.
WHERE decided_by='P' AND play_stage='R';
-- The WHERE clause filters rows where the 'decided_by' column has the value 'P' 
-- and the 'play_stage' column has the value 'R'.

Sample Output:

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

Code Explanation:

The said query in SQL that selects the count of rows from the 'match_mast' table where the "decided_by" column has the value of 'P' and the "play_stage" column has the value of 'R'.
The "COUNT" function counts the number of rows that meet the specified conditions.

Relational Algebra Expression: