Database backups with Azure SQL Database are performed for you automatically, and you have no option to perform manual database backups. To protect your data and enable point-in-time restore services, SQL Database takes full backups every week, multiple differential backups every day, and log backups every five minutes. Backup files are stored in geo-redundant storage with read access (RA-GRS) to ensure backups’ availability for disaster recovery purposes. The first full backup is scheduled immediately after a database is created. After the first full backup, all backups are scheduled automatically and managed silently in the background. The exact timing of full and differential backups is determined by the system to balance overall load.
SQL Database provides a point-in-time restore self-service feature for all databases regardless of service tier, but with different restore points as follows:
Basic: Any restore point within 7 days
Standard: Any restore point within 14 days
Premium: Any restore point within 35 days
Point-in-time restore (geo-restore) is built on top of the SQL Database automated backup system and enables you to restore an existing or deleted database to a new database as of a specified point in time. You can restore using the Azure portal, PowerShell, or the REST API. The walk-through below will demonstrate restoring a database to a point in time using the Azure portal.
When restoring an existing database, you can restore to the same logical server or to a different server. When restoring to the same server, you create a new database. Unlike SQL Server, you cannot restore over an existing database. As a result, you will have additional storage costs while both databases exist—unless you choose to delete the existing database before restoring from the backups.
Deleting a logical server also deletes all of its databases and their database backups, after which they cannot be restored regardless of the retention period discussed previously for the automated backups. To store data for longer than the period of time provided by your service tier, you will need to export data to a BACPAC file.
Source of Information : Migrating SQL Server Databases to Azure