SQL Database uses a special version of Microsoft SQL Server as its backend. It provides high availability by storing multiple copies of databases, elastic scale and rapid provisioning. It exposes a subset of the full SQL Server functionality, including only a subset of the data types — including string, numeric, date and boolean.[2] It uses an XML-based format for data transfer.[1] Like Microsoft SQL Server, SQL Database uses T-SQL as the query language and Tabular Data Stream (TDS) as the protocol to access the service over the Internet.[1][3] (The product does not provide a REST-based API to access the service over HTTP[1] - Microsoft recommends using ADO.NET Data Services for this purpose.[1])
