Is there any usage of relation data base design for mobile app which is don''t have the db?

[AC Question]

1.An android app runs with out the help of databases means, is there any necessity to create the relational database design?

2.If am using php as a back end means they have tables, databases etc., so for they only create the relational database design wright?

3.Relational database design for either database only or it will be used for design the app modules also.

Please help me thanks in advance

 

[belodion]

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