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第7章：MySQL MySQL, the most popular Open Source SQL database management system, is developed, distributed,and supported byOracle Corporation. •MySQL is a database management system. A database is a structured collectionof data. It may be anything from a simple shopping list to a picture gallery orthe vast amounts of information in a corporate network. To add, access, and processdata stored in a computer database, you need a database management system such asMySQL Server. Since computers are very good at handling large amounts of data,database management systems play a central role in computing, as standaloneutilities, or as parts of other applications. •MySQL databases are relational. A relational database stores data inseparate tables rather than putting all the data in one big storeroom. Thedatabase structures are organized into physical files optimized for speed. The logicalmodel, with objects such as databases, tables, views, rows, and columns, offersa flexible rogramming environment. You set up rules governing the relationshipsbetween different data fields, such as one-to-one, one-to-many, unique,required or optional, and “pointers” between different tables. The databaseenforces these rules, so that with a well-designed database, your applicationnever sees inconsistent, duplicate, orphan, out-of-date, or missing data. The SQL part of “MySQL” stands for “Structured Query Language”. SQL is the most common standardizedlanguage used to access databases. Depending on your programming environment, TheMain Features of MySQL you might enter SQL directly (forexample, to generate reports), embed SQL statements into code written in anotherlanguage, or use a language-specific API that hides the SQL syntax. SQL is defined by the ANSI/ISO SQLStandard. The SQL standard has been evolving since 1986 and several versionsexist. In this manual, “SQL-92” refers to the standard released in 1992, “SQL:1999”refers to the standard released in 1999, and “SQL:2003” refers to the currentversion of the standard. We use the phrase “the SQL standard” to mean thecurrent version of the SQL Standard at any time. •MySQL software is Open Source. Open Source means that it is possiblefor anyone to use and modify the software. Anybody can download the MySQLsoftware from the Internet and use it without paying anything. If you wish, youmay study the source code and change it to suit your needs. The MySQL softwareuses the GPL (GNU General Public License), http://www.fsf.org/licenses/, to define what you may and may not do with the softwarein different situations. If you feel uncomfortable with the GPL or need toembed MySQL code into a commercial application, you can buy a commerciallylicensed version from us. See the MySQL Licensing Overview for more information(http://www.mysql.com/company/legal/licensing/). •The MySQL Database Server is very fast, reliable, scalable, and easy to use. If that is what you are looking for,you should give it a try. MySQL Server can run comfortably on a desktop orlaptop, alongside your other applications, web servers, and so on, requiringlittle or no attention. If you dedicate an entire machine to MySQL, you canadjust the settings to take advantage of all the memory, CPU power, and I/Ocapacity available. MySQL can also scale up to clusters of machines, networkedtogether. MySQL Server was originally developedto handle large databases much faster than existing solutions and has beensuccessfully used in highly demanding production environments for several years.Although under constant development, MySQL Server today offers a rich anduseful set of functions. Its connectivity, speed, and security make MySQLServer highly suited for accessing databases on the Internet. • MySQL Server works inclient/server or embedded systems. The MySQL Database Software is aclient/server system that consists of a multithreaded SQL server that supportsdifferent back ends, several different client programs and libraries,administrative tools, and a wide range of application programming interfaces(APIs). We also provide MySQL Server as anembedded multithreaded library that you can link into your application to get asmaller, faster, easier-to-manage standalone product. • A large amount of contributedMySQL software is available. MySQL Server has a practical set offeatures developed in close cooperation with our users. It is very likely thatyour favorite application or language supports the MySQL Database Server. The official way to pronounce “MySQL”is “My Ess Que Ell” (not “my sequel”), but we do not mind if you pronounce itas “my sequel” or in some other localized way.
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发表于 2020-3-21 20:07:32
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