As a database, 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).
Versions:
SQL Server 2005:
SQL Server 2005 (formerly codenamed "Yukon") released in October 2005. It included native support for managing XML data, in addition to relational data.
SQL Server 2008:
SQL Server 2008 (formerly codenamed "Katmai") was released on August 6, 2008 and aims to make data management self-tuning, self organizing, and self maintaining with the development of SQL Server Always On technologies, to provide near-zero downtime.
SQL Server 2008 also includes support for structured and semi-structured data, including digital media formats for pictures, audio, video and other multimedia data.
SQL Server 2008 R2:
SQL Server 2008 R2 (10.50.1600.1, formerly codenamed "Kilimanjaro") was announced at TechEd 2009, and was released to manufacturing on April 21, 2010.
SQL Server 2008 R2 adds certain features to SQL Server 2008 including a master data management system branded as Master Data Services, a central management of master data entities and hierarchies
SQL Server 2012:
At the 2011 Professional Association for SQL Server (PASS) summit on October 11, Microsoft announced that the next major version of SQL Server (codenamed "Denali"), would be SQL Server 2012.
It was released to manufacturing on March 6, 2012.SQL Server 2012 Service Pack 1 was released to manufacturing on November 9, 2012.
It was announced to be the last version to natively support OLE DB and instead to prefer ODBC for native connectivity.
SQL Server 2014:
SQL Server 2014 is still in Community Technology Preview stage. As of November, 2013 there have been two such revisions, CTP1 and CTP2.
SQL Server 2014 will provide a new in-memory capability for tables that can fit entirely in memory (also known as Hekaton).
Development Tools:
1.SQLCMD:
SQLCMD is a command line application that comes with Microsoft SQL Server, and exposes the management features of SQL Server.
It allows SQL queries to be written and executed from the command prompt. It can also act as a scripting language to create and run a set of SQL statements as a script.
Such scripts are stored as a .sql file, and are used either for management of databases or to create the database schema during the deployment of a database.
2. SQL Server Management Studio:
SQL Server Management Studio is a GUI tool included with SQL Server 2005 and later for configuring, managing, and administering all components within Microsoft SQL Server.
The tool includes both script editors and graphical tools that work with objects and features of the server.
SQL Server Management Studio replaces Enterprise Manager as the primary management interface for Microsoft SQL Server since SQL Server 2005.
3. Business Intelligence Development Studio:
Business Intelligence Development Studio (BIDS) is the IDE from Microsoft used for developing data analysis and Business Intelligence solutions utilizing the Microsoft SQL Server Analysis Services, Reporting Services and Integration Services.
It is based on the Microsoft Visual Studio development environment but is customized with the SQL Server services-specific extensions and project types, including tools, controls and projects for reports (using Reporting Services), Cubes and data mining structures (using Analysis Services).
