Answer:
Purposes of Data Layer, in the Layered model for web applications are as following:-
1. The data Layer,is the third layer and it takes care of the all the operations concerning the database level.
2. This data layer gets a command from the application layer to send a query to the database and will process this command according to the type of database that is used.
3. It will ensure that the correct connections to the database are set.
4. It is represented by the Database.