Suman,
I think it is better not to compare DB Tables and OData model. Similarities are only upto an extent.
Few pointers
- Associations say that two entities are related. Example: Employee and Company. Associations do not have any direction. Navigation refers to an Association and says if you can navigate from Employee to Company or/and Company to Employee. A navigation from Employee to Company cannot be used other way.
- If there is a navigation defined from Employee to Company, when you fetch Employee entity, there will be a URI to navigate from Employee to Company. So Navigations actually represent navigations your UI might have.
- Navigations are used in URLs. But Associations are not.
Thanks
Krishna