SQL to find the number of distinct values in a column

Question

I can select all the distinct values in a column in the following ways:

• SELECT DISTINCT column_name FROM table_name;
• SELECT column_

Answer 1

After MS SQL Server 2012, you can use window function too.

   SELECT column_name, 
   COUNT(column_name) OVER (Partition by column_name) 
   FROM table_name group by column_name ;