Q: This question is about how can i figure or select the convenient ORM to my web application. when beginning a new web application,What are the criteria on which i can consider a specific ORM is better than another one for my project or case(web application)?

another part of my question : when i begin any web application i use three layers:

1. the DB layer (which contains the connections , and handle the CRUD operations )
2. the Managers layer(the Data Access Layer) a class for each table on my db (loosely coupled with the previous layer )it contains the CRUD operations for the specific table and the other required operations.
3. the interface layer..

and i use Object Data source.Is that considered as an ORM (as a concept) or I'm wrong in understanding this concept.

note:I still a beginner in this field ,, and every day i learn more about web development. please i want explanation and suggestions for this point.

Thanks in advance.