DQL

                                                                DQL
Data Query Language:
            This Language is used to retrieve the data from a DB server in different ways. This Language includes "SELECT" command.
There are 3 ways to retrieve data from DB 

1. Selection
2. Projection
3. Joins  

1.Selection:

                   when we required to select all the columns in the table then then we will go for selection. we can select all the columns of the table by using  selection operator ("*").

2.Projection:

                             when we required show only required columns then we will go for Projection just by specifying required columns names in the Query.

3.Joins:

                   when we required to show columns from different tables then we will go for joins