Change the database
Windows Azure Mobile Services requires a Windows Azure SQL Database instance for storing mobile service data. To change the database used by your mobile service, click Change DB and select one of the following options.
Create a new SQL Database: Mobile Services creates a new database instance for you. For an example of how to create a new SQL Database, see Get started with Mobile Services.
Use an existing SQL Database: Choose an existing database in your subscription, and then supply the Login name and Login password for the administrator of the database server.
Because SQL Database is billed by database size, you should use the smallest database that can support your app. For information about the cost of different database sizes, see the Windows Azure Pricing Calculator.
The database instance used by the mobile service is billed separately from the Mobile Services subscription. You can manage this database as you would any other SQL Database instance.