DISTINCT - Eliminating Duplicate Rows

The default display of queries is all rows, including duplicate rows.

Eliminating Duplicate Rows

Eliminate duplicate rows by using the DISTINCT keyword in the SELECT clause.

Note:

You can specify multiple columns after the DISTINCT clause. The DISTINCT clause affects all the selected columns, and the result is every distinct combination of the columns.

EX: 

Without DISTINCT the above output:  (Notice the difference)