How is Microsoft SQL Azure related to a traditional on-premises relational SQL Server database?
SQL Azure is built on SQL Server database technologies, used for running mission-critical applications in the enterprise as well as on the Web. Since SQL Server is a broad data platform that can handle all data from birth to archival, there are many capabilities that our data platform provides. SQL Azure is exposing a large subset of those relational capabilities and extending them as services in the cloud in ways that make it easy for customers and partners to consume and build upon over the Internet. In addition to this, SQL Azure provides built-in high scale, availability, utility, and other such capabilities. Although SQL Azure in its first iteration exposes only the core RDBMS capabilities of what is in the full SQL Server data platform, Microsoft expects this to increase over time, with likely future features including Reporting, Analytics, ETL and other premium services etc.