Distinct in SQL

As the name implies, the DISTINCT keyword refers to removing duplicates, preserving only non-duplicated data. If you apply the DISTINCT keyword to a column, the query results for this column will remove duplicate values.

Select  DISTINCT  from Tblperson

The keyword can be applied to one or more columns:

Select  DISTINCT  from Tblperson

The T-SQL above indicates that the combination of name and email cannot be duplicated in the query results.

Since the DISTINCT keyword can be applied on multiple columns, DISTINCT * is also legal:

Select  DISTINCT *  from Tblperson

Distinct in SQL