SQL Exercise: Within each half of play, find the number of bookings

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

27. From the following table, write a SQL query to count the number of bookings in each half of play within the normal play schedule. Return play_half, play_schedule, number of booking happened.

Sample table: player_booked

 match_no | team_id | player_id | booking_time | sent_off | play_schedule | play_half
----------+---------+-----------+--------------+----------+---------------+-----------
        1 |    1216 |    160349 |           32 |          | NT            |         1
        1 |    1216 |    160355 |           45 |          | NT            |         1
        1 |    1207 |    160159 |           69 | Y        | NT            |         2
        1 |    1216 |    160360 |           78 |          | NT            |         2
        2 |    1221 |    160470 |           14 |          | NT            |         1
        2 |    1201 |    160013 |           23 |          | NT            |         1
        2 |    1201 |    160013 |           36 |          | NT            |         1
        2 |    1201 |    160014 |           63 |          | NT            |         2
        2 |    1221 |    160472 |           66 |          | NT            |         2
.......
       51 |    1214 |    160302 |          122 |          | ET            |         2

View the table

Sample Solution:

SQL Code:

-- This SQL query calculates the count of bookings for each play half and play schedule in the 'player_booked' table.

SELECT play_half, play_schedule, COUNT(*) 
-- Selects the 'play_half', 'play_schedule', and the count of rows for each group.
FROM player_booked
-- 'player_booked' is the name of the table being queried.
WHERE play_schedule='NT'
-- The WHERE clause filters rows where the 'play_schedule' column has the value 'NT'.
GROUP BY play_half, play_schedule;
-- Groups the results by 'play_half' and 'play_schedule'.

Sample Output:

 play_half | play_schedule | count
-----------+---------------+-------
         1 | NT            |    61
         2 | NT            |   123
(2 rows)

Code Explanation:

The said query in SQL will retrieve "play_half", "play_schedule", and number of players booked in normal time schedule from the 'player_booked' table.
The WHERE clause filter the rows where the value of "play_schedule" is equal to 'NT'
A GROUP BY groups the results by play_half, play_schedule columns.

Relational Algebra Expression: