Android Database Design Considerations :

There are main two considerations specific to Android that consider when designing database:

A.)  Files (such as bitmaps or audio fi les) are not usually stored within database tables.

Instead, use a string to store a path to the fi le, preferably a fully qualifi ed Content Provider URI.

B.)  While not strictly a requirement, it’s strongly recommended that all tables include an 

auto-increment key fi eld, to function as a unique index value for each row. 

It’s worth noting that if you plan to share your table using a Content Provider, 

this unique ID fi eld is mandatory.