it英语专题数据库.doc

SQL和SQL服务器 　　SQL AND SQL SERVER 　　 IBM invented a computer language back in the 1970s designed specifically for database queries called SEQUEL；those letters stand for Structured English Query Language．Over time，the language has been added to so that it is not just a language for queries，but can also build databases and manage the database engine’s security．IBM released SEQUEL into the public domain，where it became known as SQL．Because of this heritage you can pronounce it“sequel”or spell it out“S-Q-L．”There are various versions of SQL used in today’s database engines． Microsoft SQL Server uses a version called Transact-SQL，or T-SQL，which stands for Transaction SQL． 1．What Is SQL Server?　　SQL Server is a client／server relational database management system（RDBMS）that uses Transact-SQL to send requests between a client and SQL Server．　　2．Client／Server Architecture The terms client，server，and client / server can be used to refer to very general concepts or to specific items of hardware or software．At the most general level，a client is any component of a system that requests services or resources from other components of a system．A server is any component of a system that provides services or resources to other components of a system．For example，when you print a document from your workstation on a network，the workstation is the client and the machine that does the print spooling is the server．[1]Any client／server data-based system consists of the following components：??The server一A collection of data items and supporting objects organized and presented to facilitate services，such as searching，sorting，recombining，retrieving，updating，and analyzing data．The database consists of the physical storage of data and the database services．All data access occurs through the server；the physical data is never accessed directly by the client．．The client — A software program that might be used interactively by a person or that could be an automated process．This includes all s