[radhika743]

Q.) When do we use entity beans in a project and when do we use the different types of entity beans?

[abeethabsl]

when ever your application need to maintain persistance in database side, u can use enitity beans, Entity beans are two types CMP's and BMP's.In CMP's container maintain the persistance where as in BMP's bean provider maintain the persistance.

To add, in CMP container handles queries to database and so it is good when interacting/deploying in various database environments.
While in BMP bean developer has to write SQL queries to load and store data to and from a given database table. This is the reason it is not recommended in enviroments where databases may change. Because SQL queries have to be rewritten for that database.