How to perform SELECT using COUNT in MySQL?


To perform SELECT with COUNT, use aggregate function COUNT(). Let us first create a table −

mysql> create table DemoTable
   (
   Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   Name varchar(100),
   Subject varchar(100)
   );
Query OK, 0 rows affected (0.54 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable(Name,Subject) values('John','MySQL');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(Name,Subject) values('John','Java');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(Name,Subject) values('Carol','MongoDB');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable(Name,Subject) values('Carol','Java');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(Name,Subject) values('Carol','MySQL');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable(Name,Subject) values('John','MySQL');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable(Name,Subject) values('Carol','MongoDB');
Query OK, 1 row affected (0.26 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+----+-------+---------+
| Id | Name  | Subject |
+----+-------+---------+
| 1  | John  | MySQL   |
| 2  | John  | Java    |
| 3  | Carol | MongoDB |
| 4  | Carol | Java    |
| 5  | Carol | MySQL   |
| 6  | John  | MySQL   |
| 7  | Carol | MongoDB |
+----+-------+---------+
7 rows in set (0.00 sec)

Following is the query to select using count in MySQL −

mysql> select Name,Subject,count(Subject) from DemoTable group by Subject,Name;

Output

+-------+---------+----------------+
| Name  | Subject | count(Subject) |
+-------+---------+----------------+
| John  | MySQL   | 2              |
| John  | Java    | 1              |
| Carol | MongoDB | 2              |
| Carol | Java    | 1              |
| Carol | MySQL   | 1              |
+-------+---------+----------------+
5 rows in set (0.00 sec)
raja
Published on 13-Jun-2019 11:25:27
Advertisements