Baoding-FenShuaJiang
/
Green_GoodERP18_FSJ_Standard
关注 1
点赞 0
百科 捐赠
gooderp18绿色标准版
您最多选择25个主题 主题必须以字母或数字开头，可以包含连字符 (-)，并且长度不得超过35个字符
目录树: 0f75e31513
分支列表 标签列表
${ item.name }
创建分支 ${ searchTerm }
从 '0f75e31513'
${ noResults }
Green_GoodERP18_FSJ_Standard/PostgreSQL/doc/postgresql/html/functions.html

21 行
13KB
原始文件 Blame 文件历史 

  1. <?xml version="1.0" encoding="UTF-8" standalone="no"?>

  2. <!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>Chapter 9. Functions and Operators</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 V1.79.1" /><link rel="prev" href="datatype-pseudo.html" title="8.21. Pseudo-Types" /><link rel="next" href="functions-logical.html" title="9.1. Logical Operators" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 9. Functions and Operators</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="datatype-pseudo.html" title="8.21. Pseudo-Types">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql.html" title="Part II. The SQL Language">Up</a></td><th width="60%" align="center">Part II. The SQL Language</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="functions-logical.html" title="9.1. Logical Operators">Next</a></td></tr></table><hr></hr></div><div class="chapter" id="FUNCTIONS"><div class="titlepage"><div><div><h2 class="title">Chapter 9. Functions and Operators</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="functions-logical.html">9.1. Logical Operators</a></span></dt><dt><span class="sect1"><a href="functions-comparison.html">9.2. Comparison Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-math.html">9.3. Mathematical Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-string.html">9.4. String Functions and Operators</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-string.html#FUNCTIONS-STRING-FORMAT">9.4.1. <code class="function">format</code></a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-binarystring.html">9.5. Binary String Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-bitstring.html">9.6. Bit String Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-matching.html">9.7. Pattern Matching</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-matching.html#FUNCTIONS-LIKE">9.7.1. <code class="function">LIKE</code></a></span></dt><dt><span class="sect2"><a href="functions-matching.html#FUNCTIONS-SIMILARTO-REGEXP">9.7.2. <code class="function">SIMILAR TO</code> Regular Expressions</a></span></dt><dt><span class="sect2"><a href="functions-matching.html#FUNCTIONS-POSIX-REGEXP">9.7.3. <acronym class="acronym">POSIX</acronym> Regular Expressions</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-formatting.html">9.8. Data Type Formatting Functions</a></span></dt><dt><span class="sect1"><a href="functions-datetime.html">9.9. Date/Time Functions and Operators</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT">9.9.1. <code class="function">EXTRACT</code>, <code class="function">date_part</code></a></span></dt><dt><span class="sect2"><a href="functions-datetime.html#FUNCTIONS-DATETIME-TRUNC">9.9.2. <code class="function">date_trunc</code></a></span></dt><dt><span class="sect2"><a href="functions-datetime.html#FUNCTIONS-DATETIME-ZONECONVERT">9.9.3. <code class="literal">AT TIME ZONE</code></a></span></dt><dt><span class="sect2"><a href="functions-datetime.html#FUNCTIONS-DATETIME-CURRENT">9.9.4. Current Date/Time</a></span></dt><dt><span class="sect2"><a href="functions-datetime.html#FUNCTIONS-DATETIME-DELAY">9.9.5. Delaying Execution</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-enum.html">9.10. Enum Support Functions</a></span></dt><dt><span class="sect1"><a href="functions-geometry.html">9.11. Geometric Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-net.html">9.12. Network Address Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-textsearch.html">9.13. Text Search Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-xml.html">9.14. XML Functions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-xml.html#FUNCTIONS-PRODUCING-XML">9.14.1. Producing XML Content</a></span></dt><dt><span class="sect2"><a href="functions-xml.html#FUNCTIONS-XML-PREDICATES">9.14.2. XML Predicates</a></span></dt><dt><span class="sect2"><a href="functions-xml.html#FUNCTIONS-XML-PROCESSING">9.14.3. Processing XML</a></span></dt><dt><span class="sect2"><a href="functions-xml.html#FUNCTIONS-XML-MAPPING">9.14.4. Mapping Tables to XML</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-json.html">9.15. JSON Functions and Operators</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-json.html#FUNCTIONS-JSON-PROCESSING">9.15.1. Processing and Creating JSON Data</a></span></dt><dt><span class="sect2"><a href="functions-json.html#FUNCTIONS-SQLJSON-PATH">9.15.2. The SQL/JSON Path Language</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-sequence.html">9.16. Sequence Manipulation Functions</a></span></dt><dt><span class="sect1"><a href="functions-conditional.html">9.17. Conditional Expressions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-conditional.html#FUNCTIONS-CASE">9.17.1. <code class="literal">CASE</code></a></span></dt><dt><span class="sect2"><a href="functions-conditional.html#FUNCTIONS-COALESCE-NVL-IFNULL">9.17.2. <code class="literal">COALESCE</code></a></span></dt><dt><span class="sect2"><a href="functions-conditional.html#FUNCTIONS-NULLIF">9.17.3. <code class="literal">NULLIF</code></a></span></dt><dt><span class="sect2"><a href="functions-conditional.html#FUNCTIONS-GREATEST-LEAST">9.17.4. <code class="literal">GREATEST</code> and <code class="literal">LEAST</code></a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-array.html">9.18. Array Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-range.html">9.19. Range Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-aggregate.html">9.20. Aggregate Functions</a></span></dt><dt><span class="sect1"><a href="functions-window.html">9.21. Window Functions</a></span></dt><dt><span class="sect1"><a href="functions-subquery.html">9.22. Subquery Expressions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-subquery.html#FUNCTIONS-SUBQUERY-EXISTS">9.22.1. <code class="literal">EXISTS</code></a></span></dt><dt><span class="sect2"><a href="functions-subquery.html#FUNCTIONS-SUBQUERY-IN">9.22.2. <code class="literal">IN</code></a></span></dt><dt><span class="sect2"><a href="functions-subquery.html#FUNCTIONS-SUBQUERY-NOTIN">9.22.3. <code class="literal">NOT IN</code></a></span></dt><dt><span class="sect2"><a href="functions-subquery.html#FUNCTIONS-SUBQUERY-ANY-SOME">9.22.4. <code class="literal">ANY</code>/<code class="literal">SOME</code></a></span></dt><dt><span class="sect2"><a href="functions-subquery.html#FUNCTIONS-SUBQUERY-ALL">9.22.5. <code class="literal">ALL</code></a></span></dt><dt><span class="sect2"><a href="functions-subquery.html#id-1.5.8.27.15">9.22.6. Single-Row Comparison</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-comparisons.html">9.23. Row and Array Comparisons</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-comparisons.html#FUNCTIONS-COMPARISONS-IN-SCALAR">9.23.1. <code class="literal">IN</code></a></span></dt><dt><span class="sect2"><a href="functions-comparisons.html#id-1.5.8.28.15">9.23.2. <code class="literal">NOT IN</code></a></span></dt><dt><span class="sect2"><a href="functions-comparisons.html#id-1.5.8.28.16">9.23.3. <code class="literal">ANY</code>/<code class="literal">SOME</code> (array)</a></span></dt><dt><span class="sect2"><a href="functions-comparisons.html#id-1.5.8.28.17">9.23.4. <code class="literal">ALL</code> (array)</a></span></dt><dt><span class="sect2"><a href="functions-comparisons.html#ROW-WISE-COMPARISON">9.23.5. Row Constructor Comparison</a></span></dt><dt><span class="sect2"><a href="functions-comparisons.html#COMPOSITE-TYPE-COMPARISON">9.23.6. Composite Type Comparison</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-srf.html">9.24. Set Returning Functions</a></span></dt><dt><span class="sect1"><a href="functions-info.html">9.25. System Information Functions and Operators</a></span></dt><dt><span class="sect1"><a href="functions-admin.html">9.26. System Administration Functions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-SET">9.26.1. Configuration Settings Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-SIGNAL">9.26.2. Server Signaling Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-BACKUP">9.26.3. Backup Control Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-RECOVERY-CONTROL">9.26.4. Recovery Control Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-SNAPSHOT-SYNCHRONIZATION">9.26.5. Snapshot Synchronization Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-REPLICATION">9.26.6. Replication Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-DBOBJECT">9.26.7. Database Object Management Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-INDEX">9.26.8. Index Maintenance Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADMIN-GENFILE">9.26.9. Generic File Access Functions</a></span></dt><dt><span class="sect2"><a href="functions-admin.html#FUNCTIONS-ADVISORY-LOCKS">9.26.10. Advisory Lock Functions</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-trigger.html">9.27. Trigger Functions</a></span></dt><dt><span class="sect1"><a href="functions-event-triggers.html">9.28. Event Trigger Functions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-event-triggers.html#PG-EVENT-TRIGGER-DDL-COMMAND-END-FUNCTIONS">9.28.1. Capturing Changes at Command End</a></span></dt><dt><span class="sect2"><a href="functions-event-triggers.html#PG-EVENT-TRIGGER-SQL-DROP-FUNCTIONS">9.28.2. Processing Objects Dropped by a DDL Command</a></span></dt><dt><span class="sect2"><a href="functions-event-triggers.html#PG-EVENT-TRIGGER-TABLE-REWRITE-FUNCTIONS">9.28.3. Handling a Table Rewrite Event</a></span></dt></dl></dd><dt><span class="sect1"><a href="functions-statistics.html">9.29. Statistics Information Functions</a></span></dt><dd><dl><dt><span class="sect2"><a href="functions-statistics.html#FUNCTIONS-STATISTICS-MCV">9.29.1. Inspecting MCV Lists</a></span></dt></dl></dd></dl></div><a id="id-1.5.8.2" class="indexterm"></a><a id="id-1.5.8.3" class="indexterm"></a><p>

  3.    <span class="productname">PostgreSQL</span> provides a large number of

  4.    functions and operators for the built-in data types.  Users can also

  5.    define their own functions and operators, as described in

  6.    <a class="xref" href="server-programming.html" title="Part V. Server Programming">Part V</a>.  The

  7.    <span class="application">psql</span> commands <code class="command">\df</code> and

  8.    <code class="command">\do</code> can be used to list all

  9.    available functions and operators, respectively.

  10.   </p><p>

  11.    If you are concerned about portability then note that most of

  12.    the functions and operators described in this chapter, with the

  13.    exception of the most trivial arithmetic and comparison operators

  14.    and some explicitly marked functions, are not specified by the

  15.    <acronym class="acronym">SQL</acronym> standard. Some of this extended functionality

  16.    is present in other <acronym class="acronym">SQL</acronym> database management

  17.    systems, and in many cases this functionality is compatible and

  18.    consistent between the various implementations.  This chapter is also

  19.    not exhaustive;  additional functions appear in relevant sections of

  20.    the manual.

  21.   </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="datatype-pseudo.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="functions-logical.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">8.21. Pseudo-Types </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 9.1. Logical Operators</td></tr></table></div></body></html>
上海开阖软件有限公司 沪ICP备12045867号-1