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diff --git a/doc/src/sgml/html/tutorial-concepts.html b/doc/src/sgml/html/tutorial-concepts.html new file mode 100644 index 0000000..02b8d65 --- /dev/null +++ b/doc/src/sgml/html/tutorial-concepts.html @@ -0,0 +1,37 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>2.2. Concepts</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="tutorial-sql-intro.html" title="2.1. Introduction" /><link rel="next" href="tutorial-table.html" title="2.3. Creating a New Table" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">2.2. Concepts</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="tutorial-sql-intro.html" title="2.1. Introduction">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="tutorial-sql.html" title="Chapter 2. The SQL Language">Up</a></td><th width="60%" align="center">Chapter 2. The <acronym class="acronym">SQL</acronym> Language</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="tutorial-table.html" title="2.3. Creating a New Table">Next</a></td></tr></table><hr /></div><div class="sect1" id="TUTORIAL-CONCEPTS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">2.2. Concepts</h2></div></div></div><p> + <a id="id-1.4.4.3.2.1" class="indexterm"></a> + <a id="id-1.4.4.3.2.2" class="indexterm"></a> + <a id="id-1.4.4.3.2.3" class="indexterm"></a> + <a id="id-1.4.4.3.2.4" class="indexterm"></a> + <a id="id-1.4.4.3.2.5" class="indexterm"></a> + + <span class="productname">PostgreSQL</span> is a <em class="firstterm">relational + database management system</em> (<acronym class="acronym">RDBMS</acronym>). + That means it is a system for managing data stored in + <em class="firstterm">relations</em>. Relation is essentially a + mathematical term for <em class="firstterm">table</em>. The notion of + storing data in tables is so commonplace today that it might + seem inherently obvious, but there are a number of other ways of + organizing databases. Files and directories on Unix-like + operating systems form an example of a hierarchical database. A + more modern development is the object-oriented database. + </p><p> + <a id="id-1.4.4.3.3.1" class="indexterm"></a> + <a id="id-1.4.4.3.3.2" class="indexterm"></a> + + Each table is a named collection of <em class="firstterm">rows</em>. + Each row of a given table has the same set of named + <em class="firstterm">columns</em>, + and each column is of a specific data type. Whereas columns have + a fixed order in each row, it is important to remember that SQL + does not guarantee the order of the rows within the table in any + way (although they can be explicitly sorted for display). + </p><p> + <a id="id-1.4.4.3.4.1" class="indexterm"></a> + <a id="id-1.4.4.3.4.2" class="indexterm"></a> + + Tables are grouped into databases, and a collection of databases + managed by a single <span class="productname">PostgreSQL</span> server + instance constitutes a database <em class="firstterm">cluster</em>. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="tutorial-sql-intro.html" title="2.1. Introduction">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="tutorial-sql.html" title="Chapter 2. The SQL Language">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="tutorial-table.html" title="2.3. Creating a New Table">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.1. Introduction </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 2.3. Creating a New Table</td></tr></table></div></body></html>
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