SQL Exercise: Number of matches got a result by penalty shootout
9. From the following table, write a SQL query to find the number of matches that resulted in a penalty shootout.
Sample table: penalty_shootout
kick_id | match_no | team_id | player_id | score_goal | kick_no
---------+----------+---------+-----------+------------+---------
1 | 37 | 1221 | 160467 | Y | 1
2 | 37 | 1213 | 160297 | Y | 2
3 | 37 | 1221 | 160477 | N | 3
4 | 37 | 1213 | 160298 | Y | 4
5 | 37 | 1221 | 160476 | Y | 5
6 | 37 | 1213 | 160281 | Y | 6
7 | 37 | 1221 | 160470 | Y | 7
8 | 37 | 1213 | 160287 | Y | 8
9 | 37 | 1221 | 160469 | Y | 9
10 | 37 | 1213 | 160291 | Y | 10
11 | 45 | 1214 | 160322 | Y | 1
12 | 45 | 1213 | 160297 | Y | 2
13 | 45 | 1214 | 160316 | Y | 3
14 | 45 | 1213 | 160298 | Y | 4
15 | 45 | 1214 | 160314 | Y | 5
16 | 45 | 1213 | 160281 | Y | 6
17 | 45 | 1214 | 160320 | Y | 7
18 | 45 | 1213 | 160287 | N | 8
19 | 45 | 1214 | 160321 | Y | 9
20 | 47 | 1211 | 160251 | Y | 1
21 | 47 | 1208 | 160176 | Y | 2
22 | 47 | 1211 | 160253 | N | 3
23 | 47 | 1208 | 160183 | N | 4
24 | 47 | 1211 | 160234 | Y | 5
25 | 47 | 1208 | 160177 | N | 6
26 | 47 | 1211 | 160252 | N | 7
27 | 47 | 1208 | 160173 | Y | 8
28 | 47 | 1211 | 160235 | N | 9
29 | 47 | 1208 | 160180 | N | 10
30 | 47 | 1211 | 160244 | Y | 11
31 | 47 | 1208 | 160168 | Y | 12
32 | 47 | 1211 | 160246 | Y | 13
33 | 47 | 1208 | 160169 | Y | 14
34 | 47 | 1211 | 160238 | Y | 15
35 | 47 | 1208 | 160165 | Y | 16
36 | 47 | 1211 | 160237 | N | 17
37 | 47 | 1208 | 160166 | Y | 18
Sample Solution:
-- This SQL query calculates the count of distinct 'match_no' values in the 'penalty_shootout' table.
SELECT COUNT(DISTINCT match_no)
-- COUNT(DISTINCT match_no) counts the number of unique 'match_no' values in the result set.
FROM penalty_shootout;
-- 'penalty_shootout' is the name of the table from which the distinct 'match_no' count is being calculated.
Sample Output:
count
-------
3
(1 row)
Code Explanation:
The said query in SQL that selects the count of distinct values in the match_no column of the penalty_shootout table.
The result of the query will be a single value. This query will count the number of unique matches that have penalty shootouts recorded in the penalty_shootout table.
Relational Algebra Expression:
Relational Algebra Tree:
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Sample Database: soccer
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