A DISTINCT keyword is used to filter the duplicate data from the table while retrieving the records from a table.
Example
mysql> SELECT * FROM Shopping.Customer;
+------------+--------------+------------+------------+--------+------------+-----------+
| CustomerID | CustomerName | ContactNo | Address | CityID | PostalCode | CountryID |
+------------+--------------+------------+------------+--------+------------+-----------+
| 1 | Sohan | 9999075499 | Madan Puri | 124 | 122001 | 91 |
| 2 | Ram | 9650423377 | A-487 | 11 | 110085 | 91 |
| 3 | Sham | 1111111111 | A-485 | 11 | 110085 | 91 |
| 4 | Mohan | 1234567890 | 454 | 124 | 122002 | 91 |
+------------+--------------+------------+------------+--------+------------+-----------+
mysql> SELECT DISTINCT(PostalCode) FROM Shopping.Customer;
+------------+
| PostalCode |
+------------+
| 122001 |
| 110085 |
| 122002 |
+------------+
3 rows in set (0.00 sec)