Using group by on two fields and count in MySQL?

MySQLMySQLi Database

To implement GROUP BY on two fields and count, let us create a table. The following is the query to create a table −

mysql> create table GroupByTwoFieldsDemo
   −> (
   −> Id int,
   −> Name varchar(200)
   −> );
Query OK, 0 rows affected (0.53 sec)

Let us insert some records in the table −

mysql> insert into GroupByTwoFieldsDemo values(1,'John');
Query OK, 1 row affected (0.15 sec)

mysql> insert into GroupByTwoFieldsDemo values(10,'Johnson');
Query OK, 1 row affected (0.16 sec)

mysql> insert into GroupByTwoFieldsDemo values(9,'Carol');
Query OK, 1 row affected (0.14 sec)

mysql> insert into GroupByTwoFieldsDemo values(6,'Sam');
Query OK, 1 row affected (0.16 sec)

mysql> insert into GroupByTwoFieldsDemo values(5,'David');
Query OK, 1 row affected (0.20 sec)

mysql> insert into GroupByTwoFieldsDemo values(10,'Johnson');
Query OK, 1 row affected (0.15 sec)

mysql> insert into GroupByTwoFieldsDemo values(6,'Sam');
Query OK, 1 row affected (0.17 sec)

Display all records from the table with the help of select statement. The query is as follows −

mysql> select *from GroupByTwoFieldsDemo;

The following is the output −

+------+---------+
| Id   | Name    |
+------+---------+
|    1 | John    | 
|   10 | Johnson |
|    9 | Carol   |
|    6 | Sam     |
|    5 | David   |
|   10 | Johnson |
|    6 | Sam     |
+------+---------+
7 rows in set (0.00 sec)

The following is the syntax to group by two columns and count −

select yourColumnName1,yourColumnName2,....N,count(yourColumnName1) from GroupByTwoFieldsDemo group by yourColumnName1 desc,yourColumName2;

Apply the above syntax to group by two columns and display the count of duplicate values −

mysql> select Id,Name,count(Id) from GroupByTwoFieldsDemo group by id desc,Name;

The following is the output −

+------+---------+-----------+
| Id   | Name    | count(Id) |
+------+---------+-----------+
|   10 | Johnson |         2 |
|    9 | Carol   |         1 |
|    6 | Sam     |         2 |
|    5 | David   |         1 |
|    1 | John    |         1 |
+------+---------+-----------+
5 rows in set, 1 warning (0.00 sec)
raja
Published on 11-Jan-2019 12:26:28
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