What is SQL Server?
Microsoft SQL Server is Relational database management system (RDBMS) developed and owned by Microsoft. It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network (including the Internet). There are at least a dozen different editions of Microsoft SQL Server aimed at different audiences and for different workloads (ranging from small applications that store and retrieve data on the same computer, to millions of users and computers that access huge amounts of data from the Internet at the same time).
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SQL Server 2012 Editions:
Free Editions of SQL Server:
You can download free edition of SQL Server with these links
Application to manage SQL Server:
Microsoft provides a software application named SQL Server Management Studio . This provides an Editor with intelligence and graphical management tools.