SQL Exercise: Total number of players replaced in the tournament

Last update on January 13 2026 12:20:26 (UTC/GMT +8 hours)

15. From the following table, write a SQL query to count the number of players replaced in the tournament. Return number of players as "Player Replaced".

Sample table: player_in_out

 match_no | team_id | player_id | in_out | time_in_out | play_schedule | play_half
----------+---------+-----------+--------+-------------+---------------+-----------
        1 |    1207 |    160151 | I      |          66 | NT            |         2
        1 |    1207 |    160160 | O      |          66 | NT            |         2
        1 |    1207 |    160161 | I      |          77 | NT            |         2
        1 |    1207 |    160161 | O      |          77 | NT            |         2
        1 |    1207 |    160157 | I      |           2 | ST            |         2
        1 |    1207 |    160154 | O      |           2 | ST            |         2
        1 |    1216 |    160365 | I      |          61 | NT            |         2
        1 |    1216 |    160366 | O      |          61 | NT            |         2
        1 |    1216 |    160357 | I      |          72 | NT            |         2
........
       51 |    1214 |    160316 | O      |          79 | NT            |         2

View the table

Sample Solution:

-- This SQL query calculates the count of rows in the 'player_in_out' table where the 'in_out' column has the value 'I'
-- and aliases the result as "Player Replaced".

SELECT COUNT(*) as "Player Replaced"
-- COUNT(*) is an aggregate function that counts the number of rows in a result set, and the alias is set to "Player Replaced".
FROM player_in_out
-- 'player_in_out' is the name of the table being queried.
WHERE in_out='I';
-- The WHERE clause filters rows where the 'in_out' column has the value 'I'.

Sample Output:

 Player Replaced
-----------------
             293
(1 row)

Code Explanation:

The said query in SQL that selects the count of all rows where the in_out column has a value of 'I' from the table 'player_in_out'. The query also assigns the label "Player Replaced" to the resulting count using the AS keyword.
The result of this query returns a single value representing the total number of times that a player was substituted into a match.

Go to:

PREV : Matches, one goal wins except decided by penalty kicks.
NEXT : Total number of players replaced during normal play.

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