计算机等级考试sql版本,SQL和SQL服务器（一）

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 software that interacts with the server，either requesting data from or sending data to the database．Examples are management utilities(those that are part of the SQL Server product as well as those bought separately)，ad hoc query and reporting software，custom applications，off-the-shelf applications，and Web server-based applications．

•  The communication between the client and the server一The communication between the client and the server depends largely on how the client and server are implemented．Both physical and logical layers of communication can be identified．

When you communicate with someone using the telephone，the telephone system is the physical layer and a spoken natural language is the logical layer of communication．For a data-based system，the physical layer can be a network if the server and the client are on different computers．It can be interprocess communication if the server and the client are on the same computer．The logical communication structure of the physical layer may be low-level operating system calls，a proprietary data access language，or the open structured query language(SQL)．

3．SQL Server Platforms

SQL Server runs on the operating systems shown in Fig. 7-4．The SQL Server version 7 server software runs only on the Windows 32-bit API-based operating systems，but you can use all of the operating system platforms to create and execute client applications．

SQL和SQL服务器

IBM在20世纪70年代，设计了一种专门处理数据库查询的计算机语言SEQUEL，这几个字母是结构化英语查询语言的缩写。随着时间的推移，它增加了许多功能，就不仅是一个查询语言了，还可以创建数据库，管理数据库引擎的安全。IBM把它公开发行，于是就变成了现在为大家所知的SQL。由于历史的原因SQL可以读成sequel，也可以逐字段拼成S-Q-L。在现在的数据库引擎里，已经有了好多种SQL版本。微软SQL server使用的是T-SQL，它代表的是事务SQL。

1．什么是SQL Server?

SQL Server是一个客户机／服务器关系型数据库管理系统(RDBMS)，它使用事务SQL在客户机和SQL服务器间传送请求。

2．客户机一服务器体系结构

术语客户机、服务器和客户机一服务器可以是非常广的概念或专指硬件、软件。按最一般的概念，客户机是从系统其他部件请求服务或资源的系统的任何部件；服务器是向系统其他部件提供服务或资源的任何部件。

例如，当用户从网络上的工作站打印一个文件时，工作站是客户机，用作假脱机打印的机器是服务器。

任何基于数据的客户机、服务器系统都由下列部件组成。

服务器--数据项和支持对象的汇集，其中这些对象是有组织的，并随时准备提交，以便为数据的搜索、分类、重组、检索、更新和分析之类的服务提供便利。数据库由数据的物理存储器和数据库服务组成。所有的数据访问都通过服务器进行，客户机一概不能直接访问物理数据。

客户机－－一个软件程序，该程序应该由个人交互使用或可能是一个自动进程。其中包括从数据库请求数据，或向数据库送数的与服务器交互作用的所有软件，例如管理实用程序(这些是SQL服务器产品的一部分并且是单独购买的)、特别查询和报告软件、客户应用程序、现货应用程序和基于Web服务器的应用程序。

客户机和服务器之间的通信--客户机和服务器之间的通信在很大程度上取决于客户和服务器是如何实现的。通信的物理层和逻辑层可能是一样的。

当你用电话与某人通信时，电话系统是物理层，所讲的自然语言是通信的逻辑层。对于基于数据的系统，如果服务器和客户在不同的计算机上，则物理层可以是网络。如果服务器和客户在同一台计算机上，则通信可在进程之间进行。物理层逻辑通信结构可以是低层操作系统调用，一种专用数据访问语言或开放的结构化查询语言(SQL)。

3．SQL Server平台

SQL服务器运行在如图7- 4所示的操作系统上。SQL Server第7版服务器软件只运行在32位的基于API的Windows操作系统上，但可以使用所有的操作系统平台去创建和执行客户应用程序。

下表给出了操作系统及它们如何支持或不支持SQL Server 7的更多细节。