How to select unique value in MySQL?

You can select unique value with the help of DISTINCT keyword.

The syntax is as follows

select distinct yourColumnName from yourTableName;

To understand the above syntax, let us create a table. The query to create a table is as follows

mysql> create table selectUniqueValue
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Name varchar(20),
   -> Age int
   -> );
Query OK, 0 rows affected (0.64 sec)

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

mysql> insert into selectUniqueValue(Name,Age) values('John',21);
Query OK, 1 row affected (0.18 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Carol',21);
Query OK, 1 row affected (0.13 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Sam',22);
Query OK, 1 row affected (0.10 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Mike',22);
Query OK, 1 row affected (0.16 sec)
mysql> insert into selectUniqueValue(Name,Age) values('David',22);
Query OK, 1 row affected (0.13 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Larry',23);
Query OK, 1 row affected (0.12 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Bob',23);
Query OK, 1 row affected (0.12 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Maxwell',22);
Query OK, 1 row affected (0.19 sec)
mysql> insert into selectUniqueValue(Name,Age) values('Robert',21);
Query OK, 1 row affected (0.15 sec)

Now you can display all records from the table using select statement. The query is as follows −

mysql> select *from selectUniqueValue;

The following is the output

+----+---------+------+
| Id | Name    | Age  |
+----+---------+------+
|  1 | John    |   21 |
|  2 | Carol   |   21 |
|  3 | Sam     |   22 |
|  4 | Mike    |   22 |
|  5 | David   |   22 |
|  6 | Larry   |   23 |
|  7 | Bob     |   23 |
|  8 | Maxwell |   22 |
|  9 | Robert  |   21 |
+----+---------+------+
9 rows in set (0.00 sec)

The following is the query to select unique value

mysql> select distinct Age from selectUniqueValue;

The following is the output

+------+
| Age  |
+------+
|   21 |
|   22 |
|   23 |
+------+
3 rows in set (0.00 sec)