The use of the DISTINCT or UNIQUE keyword in the SELECT list eliminates duplicate data in the result set. The following SELECT statement retrieves the ename and the corresponding job name for all rows of the EMP table.
SELECT ENAME, JOB FROM EMP;
There are 14 rows, and few of the ename have same job codes. If you want to show only the distinct job codes in the table, you write the following SELECT statement. In this example, the last row shows the UNIQUE value.
SELECT DISTINCT JOB FROM EMP;