Originally known as SQL Data Services, SQL Azure for many people is the most exciting item on the Microsoft Azure menu.

SQL Azure is an almost feature complete implementation of SQL Server 2008 Geographic data types are now supported. Unlike Table Storage, SQL Azure is completely relational, with a defined schema, supports T-SQL, and we can connect via ADO.NET or ODBC.

We can manage our SQL Azure databases through the SQL Azure Portal, directly via sqlcmd, or through SQL Server Management Studio 2008 R2. At the time of writing, SQL Server 2008 R2 is the most recent release of SQL Server, and is the only SQL Server Management Studio (SSMS) version that can completely connect to SQL Azure. Microsoft provides a SQL Azure Database Manager (formerly known as Project Houston), an online tool that is used to manage SQL Azure databases. There are also a couple of third-party tools, such as SQL Azure Manager and the Omega Web Client, for managing SQL Azure. Undoubtedly, more tools will arise as more people begin to work with SQL Azure. The SQL Azure Manager (though in Alpha testing at the time of writing) can be found at http://hanssens.org/post/SQL-Azure-Manager.aspx. The Omega Web Client (along with other great third-party tools for Azure) can be found at http://www.cerebrata.com.

Just as with SQL Server, we can have multiple databases per SQL Azure instance. Database sizes are limited, so if it's possible our application may exceed the maximum size, it's a good idea to either build in an archiving strategy and tools, or plan for a multiple SQL Azure account and multiple database solution at the beginning. Behind the scenes, and just like the storage options in Windows Azure, SQL Azure data is replicated three times to ensure availability and backup.

SQL Azure Data Sync is scheduled for final release soon. Formerly known as Project Huron, SQL Azure Data Sync enables synchronization of data between SQL Azure instances, or SQL Azure and on premises SQL Server databases.