It times back to 1980s, when Oracle had already had a very large base on database market. Microsoft, most of the people who are aware of, wanted to establish its presence in the RDBMS market to compete with Oracle. Hence the story goes on.......

 In 1987 Microsoft and Sybase started a partnership to build/sell a Database Management System, based on the then (yet to be released) Sybase DataServer product. Sybase would have the rights to the product on the Unix/Mini Platform and Microsoft would have the rights on the fledgling OS2, and any other OS developed by Microsoft.

 At the time the leader in the “PC” database systems (non mainframe/mini/UNIX) was a product from Ashton Tate called dBase. To help leverage the large dBase installed base and to give Ashton Tate a true Client Server offering, Microsoft and Ashton Tate with help from Sybase announced Ashton-Tate/Microsoft SQL Server (Sybase later renamed their product to Sybase SQL Server for UNIX and VMS), this was to be the name of the OS/2 port of Sybase DataServer.

 Version1 of Ashton-Tate/Microsoft SQL Server was shipped in 1989. Originally dBase IV was supposed to have provided a dev tool/front end for SQL Server (hence the original partnership) but the problems with dBase IV after its release later in the year led to this falling by the wayside. At this point the partnership between Microsoft and Ashton Tate was dissolved and the product became Microsoft SQL Server.

 Microsoft continued the evolution of SQL Server, adding support for Windows via SQL Server 1.1 in 1990, although almost all the work was still done by Sybase with Microsoft doing testing, project management and some minor development. Over the course of 1991 the Microsoft team was given read and then read/write access to the code to allow bug fixes to be made. The first real “partnership” release followed in 1992 and synched the Sybase 4.0 code into the OS/2 product, this was released as 4.2 and included significant code from MS as well as Sybase for the first time.

 Things started to heat up just after this release, Microsoft had been working on a 32 bit version of SQL Server and Sybase was working on what would become System 10. At this point OS/2 was becoming less viable as a platform and Microsoft already had beta versions of Windows NT that was 32 bit only, available. So the SQL Server team decided to build on the stable 4.2 code for its port to NT while Sybase continued with the new System 10 code base. Now “port” really is the wrong word to use here, NT offered lots of opportunities to make a better product by using features of the OS, the clincher was the ability to run on SMP systems by using the support provided by the OS, rather than having to write it into the database code, which is what the team did, leading to the code from the 4.2 for OS/2 and the SQL Server for NT, or SQL NT.

 By this time the value of the partnership between Microsoft and Sybase was beginning to reduce, as Sybase wanted to remain platform neutral, and Microsoft wanted to fully commit to the NT platform and only the NT platform. In addition, because of the restrictive nature of the Microsoft/Sybase agreement, Microsoft could not truly add new features without Sybase’s approval.  In 1994 the partnership was dissolved and Sybase was allowed to sell its product for the first time on OS/2 and Windows and Microsoft could take the code in any direction it wanted. Microsoft did indeed take the product in its own direction, building on the SQL Server for NT code base and releasing SQL Server 6.0 and 6.5 within 18 months, these releases involved rewriting existing code and adding new code. At this point in time SQL Server was a success in its own right with the code (and features) significantly different from the original Sybase code of the 4.2 for OS/2 version.

 During this window Microsoft decided to go “big” on the data management front, part of doing that meant building a stronger, bigger team and while the org had grown from the 1 corridor it occupied in the very early days, more needed to be done. Microsoft went out and hired some of the best and most experienced people in the database industry(Hal Berenson, Peter Spiro, David Campbell  and others from DEC, James Hamilton, Lubor Kollar and others from IBM, Bill Baker from Oracle, Pedro Celis, Pat Helland from Tandem) and paired them with the best in research(Jim Gray, Phil Bernstein and others) and some of the smartest new graduates from Database Masters and PhD programs from around the world, combing these folks with the original “soul” of the team(folks like Ron Soukup) and others from inside Microsoft allowed a great, focused team to be built and gel’d in a short space of time. Some of this team worked on 6.0/6.5 but a number of them came on line to work on what was called Sphinx, the code name for the next version of SQL Server, which was shipped as version 7.0.

 The goals for Sphinx were clear, set a new standard in ease of use for complete management of data, to do so meant building a new platform that could be extended in years to come, learning the lessons of the previous releases of SQL Server and other database platforms. To do this required a complete rewrite of the Database Engine, a new Query Processor, a new Storage Engine and a new set of Data Access APIs.

 While SQL Server had made its name as a relational database management system, with SQL Server 7.0 Microsoft wanted to provide a complete data solution, this meant adding support for OLAP via OLAP Services (the code was based on an acquisition of “Plato” from Panorama in Israel), ETL/Data Integration via DTS (the code was developed in house by the Starfighter/Tools team).

 Obviously the march of SQL Server did not stop with SQL Server 7.0, SQL Server 2000,  SQL Server 2005, SQL Server 2008, SQL Server 2008 R2 followed......

 And this is the intelligence of Microsoft. Though the idea wasnt theirs' it has emerged a gaint share in the RDBMS market.