When migrating a SQL Server user database to a SQL Server instance in an Azure virtual machine, the underlying mechanism generally uses the SQL Server backup functionality (using transactional replication also is an option, and this option is discussed in its own section later in this chapter). The options that use a variation of the SQL Server backup technology are discussed in this section.
Using database backups, you can:
Use a full database backup. For simplicity, you can perform the user database migration using a SQL Server full database backup. This method is most appropriate for small databases where the downtime is short; for scenarios in which you can afford the amount of downtime required to back up, copy, and restore the database to the SQL Server instance in the Azure virtual machine; and for scenarios in which you just want to test SQL Server in an Azure virtual machine prior to an actual migration.
Use a combination of full database and transaction log backups to minimize downtime on your production system.
Use AlwaysOn Availability Groups and create a replica of your existing on-premises user database on your Azure virtual machine (or replicas of a group of user databases that must be migrated together).
To migrate a SQL Server 2000 database to a supported configuration in an Azure virtual machine, you must first upgrade the database to SQL Server 2005 SP4 or greater. When migrating using these methods, encrypt your backups and use encrypted connections to ensure your data is secure during the migration process.
Source of Information : Migrating SQL Server Databases to Azure