JQuery Mobile and database

JQuery Mobile and database

Hello,

I'm new to JQuery mobile, i need to know what's the best database for my application knowing that :

1) I need my database to be shared with all the end users not on the client side;

2) I did already a conceptual data model with entities and associations , i don't know if i can convert this with JSON because i never use it, i often use the relational database.

and i need to know where i will stock the data and which API should i use ?? 

Also if there is any tutorials in this field please share with me 

Thank u in advance members ;)