{"id":625,"date":"2016-06-03T01:06:48","date_gmt":"2016-06-03T08:06:48","guid":{"rendered":"https:\/\/database.guide\/?p=625"},"modified":"2020-02-14T16:29:34","modified_gmt":"2020-02-14T23:29:34","slug":"what-is-sql","status":"publish","type":"post","link":"https:\/\/database.guide\/what-is-sql\/","title":{"rendered":"What is SQL?"},"content":{"rendered":"<p><dfn><abbr title=\"Structured Query Language\">SQL<\/abbr><\/dfn> is the standard language for querying data inside\u00a0a\u00a0relational database management system\u00a0(<a href=\"https:\/\/database.guide\/what-is-an-rdbms\/\">RDBMS<\/a>). It is supported by\u00a0all of the major database systems, such as <a href=\"https:\/\/database.guide\/what-is-microsoft-access\/\">Microsoft Access<\/a>, <a href=\"https:\/\/database.guide\/what-is-sql-server\/\">SQL Server<\/a>, <a href=\"https:\/\/database.guide\/what-is-mysql\/\">MySQL<\/a>, <a href=\"https:\/\/database.guide\/what-is-oracle-database\/\">Oracle<\/a>, <a href=\"https:\/\/database.guide\/what-is-postgresql\/\">PostgreSQL<\/a>, DB2, etc.<\/p>\n<p><abbr title=\"Structured Query Language\">SQL<\/abbr> is a relatively easy language to learn when compared to most programming languages. It is based on <abbr title=\"Structured Query Language\">SQL<\/abbr> &#8220;statements&#8221; that, at times, can resemble natural language.<\/p>\n<p>For example:<\/p>\n<pre>SELECT CustomerName\r\nFROM Customers\r\nWHERE CustomerId = 1\r\n<\/pre>\n<p>The above SQL statement is asking the <a href=\"https:\/\/database.guide\/what-is-a-database\/\">database<\/a> to:<\/p>\n<p style=\"padding-left: 30px;\">&#8220;<strong>Select<\/strong> the value of the\u00a0<strong>CustomerName<\/strong> <a href=\"https:\/\/database.guide\/what-is-a-column\/\">column<\/a> <strong>from<\/strong> the <strong>Customers<\/strong> <a href=\"https:\/\/database.guide\/what-is-a-table\/\">table<\/a> <strong>where<\/strong> the <strong>CustomerId<\/strong> column&#8217;s value <strong>equals<\/strong>\u00a0<strong>1<\/strong>&#8220;.<\/p>\n<p><!--more--><\/p>\n<h2>SQL Pronunciation<\/h2>\n<p><abbr title=\"Structured Query Language\">SQL<\/abbr> stands for Structured Query Language.\u00a0It\u00a0is typically pronounced in one of two ways:<\/p>\n<ul>\n<li>&#8220;ess-que-el&#8221; (i.e. spelling out each letter)<\/li>\n<li>&#8220;sequel&#8221; (as in the original spelling\/pronunciation).<\/li>\n<\/ul>\n<p>The common pronunciation of the later\u00a0is probably due\u00a0to <abbr title=\"Structured Query Language\">SQL<\/abbr>&#8216;s origins.<\/p>\n<h2>SQL History<\/h2>\n<p><abbr title=\"Structured Query Language\">SQL<\/abbr> was first\u00a0designed\u00a0in 1974 by Donald D. Chamberlin and\u00a0Raymond F. Boyce\u00a0at IBM under the name <abbr title=\"Structured English Query Language\">SEQUEL<\/abbr> (Structured English Query Language). Chamberlin and Boyce published a research paper in 1974 called \u201cSEQUEL: A Structured English Query Language\u201d.<\/p>\n<p>Although starting out as <abbr title=\"Structured English Query Language\">SEQUEL<\/abbr>, the language was later renamed to <abbr title=\"Structured Query Language\">SQL<\/abbr>, because SEQUEL was already a trademark registered by the Hawker Siddeley aircraft company.<\/p>\n<p><abbr title=\"Structured English Query Language\">SEQUEL<\/abbr> was originally designed as a more user-friendly alternative to <abbr title=\"Specifying Queries As Relational Expressions\">SQUARE<\/abbr>. <abbr title=\"Structured English Query Language\">SEQUEL<\/abbr> was intended for users who were more comfortable with an English-keyword format than with the terse mathematical notation of <abbr title=\"Specifying Queries As Relational Expressions\">SQUARE<\/abbr>.\u00a0As Chamberlin recently said of\u00a0<abbr title=\"Structured English Query Language\">SEQUEL<\/abbr>:<\/p>\n<blockquote><p>The motto of this language might be <q>Tell me what you want, not how to find it.<\/q><\/p>\n<p>We wanted to leave it up to the system to figure out how to translate this high-level concept of what the user wants, into a detailed path, or plan, for retrieving the data from the database.<\/p><\/blockquote>\n<p>Since it&#8217;s beginnings in 1974,\u00a0<abbr title=\"Structured Query Language\">SQL<\/abbr> has grown into\u00a0an international standard with hundreds of pages.<\/p>\n<h2>SQL Standard<\/h2>\n<p><abbr title=\"Structured Query Language\">SQL<\/abbr> became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987.<\/p>\n<p>The standard is\u00a0currently maintained by the\u00a0<a href=\"http:\/\/www.iso.org\/iso\/jtc1_home.html\">ISO\/IEC JTC 1<\/a> (joint technical committee of the <a href=\"http:\/\/www.iso.org\/iso\/home.html\">International Organization for Standardization (ISO)<\/a> and the <a href=\"http:\/\/www.iec.ch\/\">International Electrotechnical Commission (IEC)<\/a>).<\/p>\n<p>As of this writing, the <abbr title=\"Structured Query Language\">SQL<\/abbr> standard\u00a0is currently on its 7th revision\u00a0(<a href=\"http:\/\/www.iso.org\/iso\/home\/store\/catalogue_ics\/catalogue_detail_ics.htm?csnumber=53681\">ISO\/IEC 9075-1:2011<\/a>).<\/p>\n<h2>SQL Compatibility Between RDBMSs<\/h2>\n<p>While all the major RDBMSs support <abbr title=\"Structured Query Language\">SQL<\/abbr>, they don&#8217;t all adhere to every part of the <abbr title=\"Structured Query Language\">SQL<\/abbr> standard. Because of this, there are slight discrepancies between the different database systems in how code is written. <abbr title=\"Structured Query Language\">SQL<\/abbr> code written for one system will not necessarily be able to be used on another system without at least some modifications.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>SQL is the standard language for querying data inside\u00a0a\u00a0relational database management system\u00a0(RDBMS). It is supported by\u00a0all of the major database systems, such as Microsoft Access, SQL Server, MySQL, Oracle, PostgreSQL, DB2, etc. SQL is a relatively easy language to learn when compared to most programming languages. It is based on SQL &#8220;statements&#8221; that, at times, &#8230; <a title=\"What is SQL?\" class=\"read-more\" href=\"https:\/\/database.guide\/what-is-sql\/\" aria-label=\"Read more about What is SQL?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[18,20],"class_list":["post-625","post","type-post","status-publish","format-standard","hentry","category-sql","tag-database-terms","tag-what-is"],"_links":{"self":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/625","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/comments?post=625"}],"version-history":[{"count":10,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/625\/revisions"}],"predecessor-version":[{"id":1019,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/625\/revisions\/1019"}],"wp:attachment":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/media?parent=625"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/categories?post=625"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/tags?post=625"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}