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MySQL query to count frequency of students with the same age?
You can use COUNT(*) along with GROUP BY for this. Let us first create a table −
mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentAge int ); Query OK, 0 rows affected (0.59 sec)
Insert records in the table using insert command −
mysql> insert into DemoTable(StudentAge) values(16); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(StudentAge) values(17); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(StudentAge) values(18); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentAge) values(17); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentAge) values(17); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable(StudentAge) values(17); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(StudentAge) values(18); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(StudentAge) values(18); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(StudentAge) values(19); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(StudentAge) values(19); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable(StudentAge) values(16); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentAge) values(16); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentAge) values(15); Query OK, 1 row affected (0.16 sec)
Display all records from the table using select statement −
mysql> select * from DemoTable;
This will produce the following output −
+-----------+------------+ | StudentId | StudentAge | +-----------+------------+ | 1 | 16 | | 2 | 17 | | 3 | 18 | | 4 | 17 | | 5 | 17 | | 6 | 17 | | 7 | 18 | | 8 | 18 | | 9 | 19 | | 10 | 19 | | 11 | 16 | | 12 | 16 | | 13 | 15 | +-----------+------------+ 13 rows in set (0.00 sec)
Following is the query to count frequency −
mysql> select StudentAge,count(*) AS `AgeFrequency` from DemoTable group by StudentAge;
This will produce the following output −
+------------+--------------+ | StudentAge | AgeFrequency | +------------+--------------+ | 16 | 3 | | 17 | 4 | | 18 | 3 | | 19 | 2 | | 15 | 1 | +------------+--------------+ 5 rows in set (0.05 sec)
Updated on: 30-Jul-2019
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