MySQL Query to get count of unique values?

To count the unique values on a column, you need to use keyword DISTINCT. To understand how it is done, let us create a table. The query to create a table is as follows −

mysql> create table UniqueCountByIPAddress
   -> (
   -> Id int NOT NULL AUTO_INCREMENT,
   -> UserHits int,
   -> UserIPAddress varchar(50),
   -> PRIMARY KEY(Id)
   -> );
Query OK, 0 rows affected (0.69 sec)

Insert some records in the table using insert command. The query is as follows −

mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(10,'127.0.0.1');
Query OK, 1 row affected (0.20 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(10,'127.0.0.1');
Query OK, 1 row affected (0.20 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.1');
Query OK, 1 row affected (0.20 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.1');
Query OK, 1 row affected (0.17 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.2');
Query OK, 1 row affected (0.13 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.2');
Query OK, 1 row affected (0.20 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(30,'127.0.0.2');
Query OK, 1 row affected (0.17 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(30,'127.0.0.2');
Query OK, 1 row affected (0.28 sec)
mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(30,'127.0.0.2');
Query OK, 1 row affected (0.14 sec)

Display all records from the table using a select statement. The query is as follows −

mysql> select *from UniqueCountByIPAddress;

The following is the output −

+----+----------+--------------+
| Id | UserHits | UserIPAddress|
+----+----------+--------------+
|  1 |       10 | 127.0.0.1    |
|  2 |       10 | 127.0.0.1    |
|  3 |       20 | 127.0.0.1    |
|  4 |       20 | 127.0.0.1    |
|  5 |       20 | 127.0.0.2    |
|  6 |       20 | 127.0.0.2    |
|  7 |       30 | 127.0.0.2    |
|  8 |       30 | 127.0.0.2    |
|  9 |       30 | 127.0.0.2    |
+----+----------+--------------+

The following is the query to count the distinct value on column ‘UserIPAddress’ −

mysql> select UserHits,count(distinct UserIPAddress) as TotalHits
   -> from UniqueCountByIPAddress group by UserHits;

The following is the output −

+----------+-----------+
| UserHits | TotalHits |
+----------+-----------+
|       10 |         1 |
|       20 |         2 |
|       30 |         1 |
+----------+-----------+
3 rows in set (0.05 sec)