Count the number of distinct values in MySQL?

Let us first create a table −

mysql> create table DemoTable
   -> (
   -> Name varchar(100),
   -> Code varchar(100)
   -> );
Query OK, 0 rows affected (0.54 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('Chris','0001');
Query OK, 1 row affected (0.17 sec)

mysql> insert into DemoTable values('Robert','0002');
Query OK, 1 row affected (0.20 sec)

mysql> insert into DemoTable values('Robert','0003');
Query OK, 1 row affected (0.14 sec)

mysql> insert into DemoTable values('Chris','0001');
Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

Output

+--------+------+
| Name   | Code |
+--------+------+
| Chris  | 0001 |
| Robert | 0002 |
| Robert | 0003 |
| Chris  | 0001 |
+--------+------+
4 rows in set (0.00 sec)

Following is the query to count the number of distinct values −

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

Output

+--------+----------------------+
| Name   | count(distinct Code) |
+--------+----------------------+
| Chris  |     1                |
| Robert |     2                |
+--------+----------------------+
2 rows in set (0.06 sec)