Microsoft SQL Server is a relational database management system (RDBMS) produced by Microsoft. Its primary query language is Transact-SQL, an implementation of the ANSI/ISO standard Structured Query Language (SQL) used by both Microsoft and Sybase.
Microsoft SQL Server uses a variant of SQL called T-SQL, or Transact-SQL, an implementation of SQL-92 (the ISO standard for SQL, certified in 1992) with many extensions. T-SQL mainly adds additional syntax for use in stored procedures, and affects the syntax of transaction support. (Note that SQL standards require Atomic, Consistent, Isolated, Durable or "ACID" transactions.) Microsoft SQL Server and Sybase/ASE both communicate over networks using an application-level protocol called Tabular Data Stream (TDS). The TDS protocol has also been implemented by the FreeTDS project[2] in order to allow more kinds of client applications to communicate with Microsoft SQL Server and Sybase databases. Microsoft SQL Server also supports Open Database Connectivity (ODBC). The latest release SQL Server 2005 also supports the ability to deliver client connectivity via the Web Services SOAP[3] protocol. This allows non-Windows Clients to communicate cross platform with SQL Server. Microsoft has also released a certified JDBC[4] driver to let Java Applications like BEA and IBM WebSphere communicate with Microsoft SQL Server 2000 and 2005.
SQL Server includes support for database mirroring and clustering. A SQL server cluster is a collection of identically configured servers, which help distribute the workload among multiple servers. All the servers share an identical virtual server name, and it is resolved into the IP address of any of the identically configured machines by the clustering runtime.[5] Automatic failover clustering is also available, in which the workload of a server is transferred to another system in the event of a system failure.[6] SQL server also supports data partitioning for distributed databases. Database mirroring, introduced in SQL Server 2005, allows creation of mirrors (or replicas) of database contents, along with transaction logs, on another instance of SQL Server, based on certain predefined triggers.[7] SQL Server 2005 also allows creation of snapshots, which are like backup images that can be reverted back to when needed.
SQL Server supports data replication, spanning three different scenarios:
1. Snapshot replication:[8] Snapshots of a database is pushed out to all replication subscribers of a server.
2. Transaction replication:[8] Changes to the database is continually published out to clients.
3. Merge replication:[8]Synchronizing the database with other servers participating in the replication. Changes to all databases happen independently and during replication, the changes are synchronized among all databases. Merge replication includes in-built support for conflict resolution.[8]
SQL Server 2005 introduced support for .NET Framework. With this, stored procedures could be written in any .NET language, using the entire set of libraries available to the .NET Framework, as well the Common Type System. However, unlike other processes, .NET Framework hosted in SQL Server 2005 utilizes memory and thread management capabilities provided by SQL Server, rather than using built in capabilities of Windows. This enhances performance as resource management algorithms are tuned for the usage pattern of SQL Server, as compared to the generic algorithms in Windows.
Application development
Microsoft and other vendors provide a number of software development tools designed to allow business applications to be developed using the data stored by Microsoft SQL Server. Microsoft SQL Server 2005 now includes the common language runtime (CLR) component for Microsoft .NET. Applications developed with .NET languages such as C# can implement stored procedures and other functions. Older versions of Microsoft development tools typically use APIs to access Microsoft SQL Server functionality. Rapid application development tools such as eDeveloper by Magic Software Enterprises incorporate native database gateways for high speed database access and automatic table drill-down for the creation of quick prototype applications for viewing, editing and adding data to any table in the database.
SQL Server Express Edition
Main article: SQL Server Express
Formerly known as MSDE, Microsoft SQL Server Express is Microsoft's freely-downloadable and distributable version of its database engine; it has some technical restrictions that make it unsuited for large-scale deployments. It is primarily used for desktop applications, prototyping, or self study.
Versions and Editions
SQL Server 7.0
* Enterprise Edition
* Developer Edition
* Standard Edition
SQL Server 2000
* Enterprise Edition
* Developer Edition
* Standard Edition
* Workgroup Edition
* Personal Edition
* Desktop Engine (MSDE 2000)
* Server CE
SQL Server 2005
(Compare features)
* Enterprise Edition (x86, x64, and IA64)
* Developer Edition (x86, x64, and IA64)
* Standard Edition (x86, x64, and IA64)
* Workgroup Edition (x86 only)
* Express Edition (x86 and x64)
* Mobile Edition
* Compact Edition
SQL Server 2008
* SQL Server 2008
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