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<!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>9.4. String 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="functions-math.html" title="9.3. Mathematical Functions and Operators" /><link rel="next" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators" /></head><body id="docContent" class="container-fluid col-10"><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">9.4. String Functions and Operators</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="functions-math.html" title="9.3. Mathematical Functions and Operators">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><th width="60%" align="center">Chapter 9. Functions and Operators</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 13.1 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="FUNCTIONS-STRING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9.4. String Functions and Operators</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="functions-string.html#FUNCTIONS-STRING-FORMAT">9.4.1. <code class="function">format</code></a></span></dt></dl></div><p>
    This section describes functions and operators for examining and
    manipulating string values.  Strings in this context include values
    of the types <code class="type">character</code>, <code class="type">character varying</code>,
    and <code class="type">text</code>.  Except where noted, these functions and operators
    are declared to accept and return type <code class="type">text</code>.  They will
    interchangeably accept <code class="type">character varying</code> arguments.
    Values of type <code class="type">character</code> will be converted
    to <code class="type">text</code> before the function or operator is applied, resulting
    in stripping any trailing spaces in the <code class="type">character</code> value.
   </p><p>
    <acronym class="acronym">SQL</acronym> defines some string functions that use
    key words, rather than commas, to separate
    arguments.  Details are in
    <a class="xref" href="functions-string.html#FUNCTIONS-STRING-SQL" title="Table 9.9. SQL String Functions and Operators">Table 9.9</a>.
    <span class="productname">PostgreSQL</span> also provides versions of these functions
    that use the regular function invocation syntax
    (see <a class="xref" href="functions-string.html#FUNCTIONS-STRING-OTHER" title="Table 9.10. Other String Functions">Table 9.10</a>).
   </p><div class="note"><h3 class="title">Note</h3><p>
     Before <span class="productname">PostgreSQL</span> 8.3, these functions would
     silently accept values of several non-string data types as well, due to
     the presence of implicit coercions from those data types to
     <code class="type">text</code>.  Those coercions have been removed because they frequently
     caused surprising behaviors.  However, the string concatenation operator
     (<code class="literal">||</code>) still accepts non-string input, so long as at least one
     input is of a string type, as shown in <a class="xref" href="functions-string.html#FUNCTIONS-STRING-SQL" title="Table 9.9. SQL String Functions and Operators">Table 9.9</a>.  For other cases, insert an explicit
     coercion to <code class="type">text</code> if you need to duplicate the previous behavior.
    </p></div><div class="table" id="FUNCTIONS-STRING-SQL"><p class="title"><strong>Table 9.9. <acronym class="acronym">SQL</acronym> String Functions and Operators</strong></p><div class="table-contents"><table class="table" summary="SQL String Functions and Operators" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
        Function/Operator
       </p>
       <p>
        Description
       </p>
       <p>
        Example(s)
       </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.1.1.1.1" class="indexterm"></a>
        <code class="type">text</code> <code class="literal">||</code> <code class="type">text</code>
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Concatenates the two strings.
       </p>
       <p>
        <code class="literal">'Post' || 'greSQL'</code>
        → <code class="returnvalue">PostgreSQL</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="type">text</code> <code class="literal">||</code> <code class="type">anynonarray</code>
        → <code class="returnvalue">text</code>
       </p>
       <p class="func_signature">
        <code class="type">anynonarray</code> <code class="literal">||</code> <code class="type">text</code>
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the non-string input to text, then concatenates the two
        strings.  (The non-string input cannot be of an array type, because
        that would create ambiguity with the array <code class="literal">||</code>
        operators.  If you want to concatenate an array's text equivalent,
        cast it to <code class="type">text</code> explicitly.)
       </p>
       <p>
        <code class="literal">'Value: ' || 42</code>
        → <code class="returnvalue">Value: 42</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.3.1.1.1" class="indexterm"></a>
        <a id="id-1.5.8.10.5.2.2.3.1.1.2" class="indexterm"></a>
         <code class="type">text</code> <code class="literal">IS</code> [<span class="optional"><code class="literal">NOT</code></span>] [<span class="optional"><em class="parameter"><code>form</code></em></span>] <code class="literal">NORMALIZED</code>
        → <code class="returnvalue">boolean</code>
       </p>
       <p>
        Checks whether the string is in the specified Unicode normalization
        form.  The optional <em class="parameter"><code>form</code></em> key word specifies the
        form: <code class="literal">NFC</code> (the default), <code class="literal">NFD</code>,
        <code class="literal">NFKC</code>, or <code class="literal">NFKD</code>.  This expression can
        only be used when the server encoding is <code class="literal">UTF8</code>.  Note
        that checking for normalization using this expression is often faster
        than normalizing possibly already normalized strings.
       </p>
       <p>
        <code class="literal">U&amp;'\0061\0308bc' IS NFD NORMALIZED</code>
        → <code class="returnvalue">t</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.4.1.1.1" class="indexterm"></a>
        <code class="function">bit_length</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns number of bits in the string (8
        times the <code class="function">octet_length</code>).
       </p>
       <p>
        <code class="literal">bit_length('jose')</code>
        → <code class="returnvalue">32</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.5.1.1.1" class="indexterm"></a>
        <a id="id-1.5.8.10.5.2.2.5.1.1.2" class="indexterm"></a>
        <a id="id-1.5.8.10.5.2.2.5.1.1.3" class="indexterm"></a>
        <code class="function">char_length</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.5.1.2.1" class="indexterm"></a>
        <code class="function">character_length</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns number of characters in the string.
       </p>
       <p>
        <code class="literal">char_length('josé')</code>
        → <code class="returnvalue">4</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.6.1.1.1" class="indexterm"></a>
        <code class="function">lower</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the string to all lower case, according to the rules of the
        database's locale.
       </p>
       <p>
        <code class="literal">lower('TOM')</code>
        → <code class="returnvalue">tom</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.7.1.1.1" class="indexterm"></a>
        <a id="id-1.5.8.10.5.2.2.7.1.1.2" class="indexterm"></a>
        <code class="function">normalize</code> ( <code class="type">text</code>
        [<span class="optional">, <em class="parameter"><code>form</code></em> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the string to the specified Unicode
        normalization form.  The optional <em class="parameter"><code>form</code></em> key word
        specifies the form: <code class="literal">NFC</code> (the default),
        <code class="literal">NFD</code>, <code class="literal">NFKC</code>, or
        <code class="literal">NFKD</code>.  This function can only be used when the
        server encoding is <code class="literal">UTF8</code>.
       </p>
       <p>
        <code class="literal">normalize(U&amp;'\0061\0308bc', NFC)</code>
        → <code class="returnvalue">U&amp;'\00E4bc'</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.8.1.1.1" class="indexterm"></a>
        <code class="function">octet_length</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns number of bytes in the string.
       </p>
       <p>
        <code class="literal">octet_length('josé')</code>
        → <code class="returnvalue">5</code> (if server encoding is UTF8)
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.9.1.1.1" class="indexterm"></a>
        <code class="function">octet_length</code> ( <code class="type">character</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns number of bytes in the string.  Since this version of the
        function accepts type <code class="type">character</code> directly, it will not
        strip trailing spaces.
       </p>
       <p>
        <code class="literal">octet_length('abc '::character(4))</code>
        → <code class="returnvalue">4</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.10.1.1.1" class="indexterm"></a>
        <code class="function">overlay</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code> <code class="literal">PLACING</code> <em class="parameter"><code>newsubstring</code></em> <code class="type">text</code> <code class="literal">FROM</code> <em class="parameter"><code>start</code></em> <code class="type">integer</code> [<span class="optional"> <code class="literal">FOR</code> <em class="parameter"><code>count</code></em> <code class="type">integer</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Replaces the substring of <em class="parameter"><code>string</code></em> that starts at
        the <em class="parameter"><code>start</code></em>'th character and extends
        for <em class="parameter"><code>count</code></em> characters
        with <em class="parameter"><code>newsubstring</code></em>.
        If <em class="parameter"><code>count</code></em> is omitted, it defaults to the length
        of <em class="parameter"><code>newsubstring</code></em>.
       </p>
       <p>
        <code class="literal">overlay('Txxxxas' placing 'hom' from 2 for 4)</code>
        → <code class="returnvalue">Thomas</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.11.1.1.1" class="indexterm"></a>
        <code class="function">position</code> ( <em class="parameter"><code>substring</code></em> <code class="type">text</code> <code class="literal">IN</code> <em class="parameter"><code>string</code></em> <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns starting index of specified <em class="parameter"><code>substring</code></em>
        within <em class="parameter"><code>string</code></em>, or zero if it's not present.
       </p>
       <p>
        <code class="literal">position('om' in 'Thomas')</code>
        → <code class="returnvalue">3</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.12.1.1.1" class="indexterm"></a>
        <code class="function">substring</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code> [<span class="optional"> <code class="literal">FROM</code> <em class="parameter"><code>start</code></em> <code class="type">integer</code> </span>] [<span class="optional"> <code class="literal">FOR</code> <em class="parameter"><code>count</code></em> <code class="type">integer</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extracts the substring of <em class="parameter"><code>string</code></em> starting at
        the <em class="parameter"><code>start</code></em>'th character if that is specified,
        and stopping after <em class="parameter"><code>count</code></em> characters if that is
        specified.  Provide at least one of <em class="parameter"><code>start</code></em>
        and <em class="parameter"><code>count</code></em>.
       </p>
       <p>
        <code class="literal">substring('Thomas' from 2 for 3)</code>
        → <code class="returnvalue">hom</code>
       </p>
       <p>
        <code class="literal">substring('Thomas' from 3)</code>
        → <code class="returnvalue">omas</code>
       </p>
       <p>
        <code class="literal">substring('Thomas' for 2)</code>
        → <code class="returnvalue">Th</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="function">substring</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code> <code class="literal">FROM</code> <em class="parameter"><code>pattern</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extracts substring matching POSIX regular expression; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">substring('Thomas' from '...$')</code>
        → <code class="returnvalue">mas</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="function">substring</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code> <code class="literal">FROM</code> <em class="parameter"><code>pattern</code></em> <code class="type">text</code> <code class="literal">FOR</code> <em class="parameter"><code>escape</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extracts substring matching <acronym class="acronym">SQL</acronym> regular expression;
        see <a class="xref" href="functions-matching.html#FUNCTIONS-SIMILARTO-REGEXP" title="9.7.2. SIMILAR TO Regular Expressions">Section 9.7.2</a>.
       </p>
       <p>
        <code class="literal">substring('Thomas' from '%#"o_a#"_' for '#')</code>
        → <code class="returnvalue">oma</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.15.1.1.1" class="indexterm"></a>
        <code class="function">trim</code> ( [<span class="optional"> <code class="literal">LEADING</code> | <code class="literal">TRAILING</code> | <code class="literal">BOTH</code> </span>]
        [<span class="optional"> <em class="parameter"><code>characters</code></em> <code class="type">text</code> </span>] <code class="literal">FROM</code>
        <em class="parameter"><code>string</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Removes the longest string containing only characters in
        <em class="parameter"><code>characters</code></em> (a space by default) from the
        start, end, or both ends (<code class="literal">BOTH</code> is the default)
        of <em class="parameter"><code>string</code></em>.
       </p>
       <p>
        <code class="literal">trim(both 'xyz' from 'yxTomxx')</code>
        → <code class="returnvalue">Tom</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="function">trim</code> ( [<span class="optional"> <code class="literal">LEADING</code> | <code class="literal">TRAILING</code> | <code class="literal">BOTH</code> </span>] [<span class="optional"> <code class="literal">FROM</code> </span>]
        <em class="parameter"><code>string</code></em> <code class="type">text</code> [<span class="optional">,
        <em class="parameter"><code>characters</code></em> <code class="type">text</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        This is a non-standard syntax for <code class="function">trim()</code>.
       </p>
       <p>
        <code class="literal">trim(both from 'yxTomxx', 'xyz')</code>
        → <code class="returnvalue">Tom</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.5.2.2.17.1.1.1" class="indexterm"></a>
        <code class="function">upper</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the string to all upper case, according to the rules of the
        database's locale.
       </p>
       <p>
        <code class="literal">upper('tom')</code>
        → <code class="returnvalue">TOM</code>
       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
    Additional string manipulation functions are available and are
    listed in <a class="xref" href="functions-string.html#FUNCTIONS-STRING-OTHER" title="Table 9.10. Other String Functions">Table 9.10</a>.  Some of them are used internally to implement the
    <acronym class="acronym">SQL</acronym>-standard string functions listed in <a class="xref" href="functions-string.html#FUNCTIONS-STRING-SQL" title="Table 9.9. SQL String Functions and Operators">Table 9.9</a>.
   </p><div class="table" id="FUNCTIONS-STRING-OTHER"><p class="title"><strong>Table 9.10. Other String Functions</strong></p><div class="table-contents"><table class="table" summary="Other String Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
        Function
       </p>
       <p>
        Description
       </p>
       <p>
        Example(s)
       </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.1.1.1.1" class="indexterm"></a>
        <code class="function">ascii</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns the numeric code of the first character of the argument.
        In <acronym class="acronym">UTF8</acronym> encoding, returns the Unicode code point
        of the character.  In other multibyte encodings, the argument must
        be an <acronym class="acronym">ASCII</acronym> character.
       </p>
       <p>
        <code class="literal">ascii('x')</code>
        → <code class="returnvalue">120</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.2.1.1.1" class="indexterm"></a>
        <code class="function">btrim</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>
        [<span class="optional">, <em class="parameter"><code>characters</code></em> <code class="type">text</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Removes the longest string containing only characters
        in <em class="parameter"><code>characters</code></em> (a space by default)
        from the start and end of <em class="parameter"><code>string</code></em>.
       </p>
       <p>
        <code class="literal">btrim('xyxtrimyyx', 'xyz')</code>
        → <code class="returnvalue">trim</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.3.1.1.1" class="indexterm"></a>
        <code class="function">chr</code> ( <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns the character with the given code. In <acronym class="acronym">UTF8</acronym>
        encoding the argument is treated as a Unicode code point. In other
        multibyte encodings the argument must designate
        an <acronym class="acronym">ASCII</acronym> character.  <code class="literal">chr(0)</code> is
        disallowed because text data types cannot store that character.
      </p>
      <p>
        <code class="literal">chr(65)</code>
        → <code class="returnvalue">A</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.4.1.1.1" class="indexterm"></a>
        <code class="function">concat</code> ( <em class="parameter"><code>val1</code></em> <code class="type">"any"</code>
         [, <em class="parameter"><code>val2</code></em> <code class="type">"any"</code> [, ...] ] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Concatenates the text representations of all the arguments.
        NULL arguments are ignored.
       </p>
       <p>
        <code class="literal">concat('abcde', 2, NULL, 22)</code>
        → <code class="returnvalue">abcde222</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.5.1.1.1" class="indexterm"></a>
        <code class="function">concat_ws</code> ( <em class="parameter"><code>sep</code></em> <code class="type">text</code>,
        <em class="parameter"><code>val1</code></em> <code class="type">"any"</code>
        [, <em class="parameter"><code>val2</code></em> <code class="type">"any"</code> [, ...] ] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Concatenates all but the first argument, with separators. The first
        argument is used as the separator string, and should not be NULL.
        Other NULL arguments are ignored.
       </p>
       <p>
        <code class="literal">concat_ws(',', 'abcde', 2, NULL, 22)</code>
        → <code class="returnvalue">abcde,2,22</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.6.1.1.1" class="indexterm"></a>
        <code class="function">format</code> ( <em class="parameter"><code>formatstr</code></em> <code class="type">text</code>
        [, <em class="parameter"><code>formatarg</code></em> <code class="type">"any"</code> [, ...] ] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
         Formats arguments according to a format string;
         see <a class="xref" href="functions-string.html#FUNCTIONS-STRING-FORMAT" title="9.4.1. format">Section 9.4.1</a>.
         This function is similar to the C function <code class="function">sprintf</code>.
       </p>
       <p>
        <code class="literal">format('Hello %s, %1$s', 'World')</code>
        → <code class="returnvalue">Hello World, World</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.7.1.1.1" class="indexterm"></a>
        <code class="function">initcap</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the first letter of each word to upper case and the
        rest to lower case. Words are sequences of alphanumeric
        characters separated by non-alphanumeric characters.
       </p>
       <p>
        <code class="literal">initcap('hi THOMAS')</code>
        → <code class="returnvalue">Hi Thomas</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.8.1.1.1" class="indexterm"></a>
        <code class="function">left</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>n</code></em> <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns first <em class="parameter"><code>n</code></em> characters in the
        string, or when <em class="parameter"><code>n</code></em> is negative, returns
        all but last |<em class="parameter"><code>n</code></em>| characters.
       </p>
       <p>
        <code class="literal">left('abcde', 2)</code>
        → <code class="returnvalue">ab</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.9.1.1.1" class="indexterm"></a>
        <code class="function">length</code> ( <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns the number of characters in the string.
       </p>
       <p>
        <code class="literal">length('jose')</code>
        → <code class="returnvalue">4</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.10.1.1.1" class="indexterm"></a>
        <code class="function">lpad</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>length</code></em> <code class="type">integer</code>
        [<span class="optional">, <em class="parameter"><code>fill</code></em> <code class="type">text</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extends the <em class="parameter"><code>string</code></em> to length
        <em class="parameter"><code>length</code></em> by prepending the characters
        <em class="parameter"><code>fill</code></em> (a space by default).  If the
        <em class="parameter"><code>string</code></em> is already longer than
        <em class="parameter"><code>length</code></em> then it is truncated (on the right).
       </p>
       <p>
        <code class="literal">lpad('hi', 5, 'xy')</code>
        → <code class="returnvalue">xyxhi</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.11.1.1.1" class="indexterm"></a>
        <code class="function">ltrim</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>
        [<span class="optional">, <em class="parameter"><code>characters</code></em> <code class="type">text</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Removes the longest string containing only characters in
        <em class="parameter"><code>characters</code></em> (a space by default) from the start of
        <em class="parameter"><code>string</code></em>.
       </p>
       <p>
        <code class="literal">ltrim('zzzytest', 'xyz')</code>
        → <code class="returnvalue">test</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.12.1.1.1" class="indexterm"></a>
        <code class="function">md5</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Computes the MD5 <a class="link" href="functions-binarystring.html#FUNCTIONS-HASH-NOTE">hash</a> of
        the argument, with the result written in hexadecimal.
       </p>
       <p>
        <code class="literal">md5('abc')</code>
        → <code class="returnvalue">900150983cd24fb0d6963f7d28e17f72</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.13.1.1.1" class="indexterm"></a>
        <code class="function">parse_ident</code> ( <em class="parameter"><code>qualified_identifier</code></em> <code class="type">text</code>
        [, <em class="parameter"><code>strict_mode</code></em> <code class="type">boolean</code> <code class="literal">DEFAULT</code> <code class="literal">true</code> ] )
        → <code class="returnvalue">text[]</code>
       </p>
       <p>
        Splits <em class="parameter"><code>qualified_identifier</code></em> into an array of
        identifiers, removing any quoting of individual identifiers.  By
        default, extra characters after the last identifier are considered an
        error; but if the second parameter is <code class="literal">false</code>, then such
        extra characters are ignored. (This behavior is useful for parsing
        names for objects like functions.) Note that this function does not
        truncate over-length identifiers. If you want truncation you can cast
        the result to <code class="type">name[]</code>.
       </p>
       <p>
        <code class="literal">parse_ident('"SomeSchema".someTable')</code>
        → <code class="returnvalue">{SomeSchema,sometable}</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.14.1.1.1" class="indexterm"></a>
        <code class="function">pg_client_encoding</code> ( )
        → <code class="returnvalue">name</code>
       </p>
       <p>
        Returns current client encoding name.
       </p>
       <p>
        <code class="literal">pg_client_encoding()</code>
        → <code class="returnvalue">UTF8</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.15.1.1.1" class="indexterm"></a>
        <code class="function">quote_ident</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns the given string suitably quoted to be used as an identifier
        in an <acronym class="acronym">SQL</acronym> statement string.
        Quotes are added only if necessary (i.e., if the string contains
        non-identifier characters or would be case-folded).
        Embedded quotes are properly doubled.
        See also <a class="xref" href="plpgsql-statements.html#PLPGSQL-QUOTE-LITERAL-EXAMPLE" title="Example 42.1. Quoting Values in Dynamic Queries">Example 42.1</a>.
       </p>
       <p>
        <code class="literal">quote_ident('Foo bar')</code>
        → <code class="returnvalue">"Foo bar"</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.16.1.1.1" class="indexterm"></a>
        <code class="function">quote_literal</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns the given string suitably quoted to be used as a string literal
        in an <acronym class="acronym">SQL</acronym> statement string.
        Embedded single-quotes and backslashes are properly doubled.
        Note that <code class="function">quote_literal</code> returns null on null
        input; if the argument might be null,
        <code class="function">quote_nullable</code> is often more suitable.
        See also <a class="xref" href="plpgsql-statements.html#PLPGSQL-QUOTE-LITERAL-EXAMPLE" title="Example 42.1. Quoting Values in Dynamic Queries">Example 42.1</a>.
       </p>
       <p>
        <code class="literal">quote_literal(E'O\'Reilly')</code>
        → <code class="returnvalue">'O''Reilly'</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="function">quote_literal</code> ( <code class="type">anyelement</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the given value to text and then quotes it as a literal.
        Embedded single-quotes and backslashes are properly doubled.
       </p>
       <p>
        <code class="literal">quote_literal(42.5)</code>
        → <code class="returnvalue">'42.5'</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.18.1.1.1" class="indexterm"></a>
        <code class="function">quote_nullable</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns the given string suitably quoted to be used as a string literal
        in an <acronym class="acronym">SQL</acronym> statement string; or, if the argument
        is null, returns <code class="literal">NULL</code>.
        Embedded single-quotes and backslashes are properly doubled.
        See also <a class="xref" href="plpgsql-statements.html#PLPGSQL-QUOTE-LITERAL-EXAMPLE" title="Example 42.1. Quoting Values in Dynamic Queries">Example 42.1</a>.
       </p>
       <p>
        <code class="literal">quote_nullable(NULL)</code>
        → <code class="returnvalue">NULL</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <code class="function">quote_nullable</code> ( <code class="type">anyelement</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the given value to text and then quotes it as a literal;
        or, if the argument is null, returns <code class="literal">NULL</code>.
        Embedded single-quotes and backslashes are properly doubled.
       </p>
       <p>
        <code class="literal">quote_nullable(42.5)</code>
        → <code class="returnvalue">'42.5'</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.20.1.1.1" class="indexterm"></a>
        <code class="function">regexp_match</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>pattern</code></em> <code class="type">text</code> [, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
        → <code class="returnvalue">text[]</code>
       </p>
       <p>
        Returns captured substring(s) resulting from the first match of a POSIX
        regular expression to the <em class="parameter"><code>string</code></em>; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">regexp_match('foobarbequebaz', '(bar)(beque)')</code>
        → <code class="returnvalue">{bar,beque}</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.21.1.1.1" class="indexterm"></a>
        <code class="function">regexp_matches</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>pattern</code></em> <code class="type">text</code> [, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
        → <code class="returnvalue">setof text[]</code>
       </p>
       <p>
        Returns captured substring(s) resulting from matching a POSIX regular
        expression to the <em class="parameter"><code>string</code></em>; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">regexp_matches('foobarbequebaz', 'ba.', 'g')</code>
        → <code class="returnvalue"></code>
</p><pre class="programlisting">
 {bar}
 {baz}
</pre><p>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.22.1.1.1" class="indexterm"></a>
        <code class="function">regexp_replace</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>pattern</code></em> <code class="type">text</code>, <em class="parameter"><code>replacement</code></em> <code class="type">text</code> [, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Replaces substring(s) matching a POSIX regular expression; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">regexp_replace('Thomas', '.[mN]a.', 'M')</code>
        → <code class="returnvalue">ThM</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.23.1.1.1" class="indexterm"></a>
        <code class="function">regexp_split_to_array</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>pattern</code></em> <code class="type">text</code> [, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
        → <code class="returnvalue">text[]</code>
       </p>
       <p>
        Splits <em class="parameter"><code>string</code></em> using a POSIX regular
        expression as the delimiter; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">regexp_split_to_array('hello world', '\s+')</code>
        → <code class="returnvalue">{hello,world}</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.24.1.1.1" class="indexterm"></a>
        <code class="function">regexp_split_to_table</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>pattern</code></em> <code class="type">text</code> [, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
        → <code class="returnvalue">setof text</code>
       </p>
       <p>
        Splits <em class="parameter"><code>string</code></em> using a POSIX regular
        expression as the delimiter; see
        <a class="xref" href="functions-matching.html#FUNCTIONS-POSIX-REGEXP" title="9.7.3. POSIX Regular Expressions">Section 9.7.3</a>.
       </p>
       <p>
        <code class="literal">regexp_split_to_table('hello world', '\s+')</code>
        → <code class="returnvalue"></code>
</p><pre class="programlisting">
 hello
 world
</pre><p>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.25.1.1.1" class="indexterm"></a>
        <code class="function">repeat</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>number</code></em> <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Repeats <em class="parameter"><code>string</code></em> the specified
        <em class="parameter"><code>number</code></em> of times.
       </p>
       <p>
        <code class="literal">repeat('Pg', 4)</code>
        → <code class="returnvalue">PgPgPgPg</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.26.1.1.1" class="indexterm"></a>
        <code class="function">replace</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>from</code></em> <code class="type">text</code>,
        <em class="parameter"><code>to</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Replaces all occurrences in <em class="parameter"><code>string</code></em> of
        substring <em class="parameter"><code>from</code></em> with
        substring <em class="parameter"><code>to</code></em>.
       </p>
       <p>
        <code class="literal">replace('abcdefabcdef', 'cd', 'XX')</code>
        → <code class="returnvalue">abXXefabXXef</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.27.1.1.1" class="indexterm"></a>
        <code class="function">reverse</code> ( <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Reverses the order of the characters in the string.
       </p>
       <p>
        <code class="literal">reverse('abcde')</code>
        → <code class="returnvalue">edcba</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.28.1.1.1" class="indexterm"></a>
        <code class="function">right</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
         <em class="parameter"><code>n</code></em> <code class="type">integer</code> )
<code class="type"></code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Returns last <em class="parameter"><code>n</code></em> characters in the string,
        or when <em class="parameter"><code>n</code></em> is negative, returns all but
        first |<em class="parameter"><code>n</code></em>| characters.
       </p>
       <p>
        <code class="literal">right('abcde', 2)</code>
        → <code class="returnvalue">de</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.29.1.1.1" class="indexterm"></a>
        <code class="function">rpad</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>length</code></em> <code class="type">integer</code>
        [<span class="optional">, <em class="parameter"><code>fill</code></em> <code class="type">text</code> </span>] )
<code class="type"></code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extends the <em class="parameter"><code>string</code></em> to length
        <em class="parameter"><code>length</code></em> by appending the characters
        <em class="parameter"><code>fill</code></em> (a space by default).  If the
        <em class="parameter"><code>string</code></em> is already longer than
        <em class="parameter"><code>length</code></em> then it is truncated.
       </p>
       <p>
        <code class="literal">rpad('hi', 5, 'xy')</code>
        → <code class="returnvalue">hixyx</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.30.1.1.1" class="indexterm"></a>
        <code class="function">rtrim</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>
         [<span class="optional">, <em class="parameter"><code>characters</code></em> <code class="type">text</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Removes the longest string containing only characters in
        <em class="parameter"><code>characters</code></em> (a space by default) from the end of
        <em class="parameter"><code>string</code></em>.
       </p>
       <p>
        <code class="literal">rtrim('testxxzx', 'xyz')</code>
        → <code class="returnvalue">test</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.31.1.1.1" class="indexterm"></a>
        <code class="function">split_part</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>delimiter</code></em> <code class="type">text</code>,
        <em class="parameter"><code>n</code></em> <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Splits <em class="parameter"><code>string</code></em> at occurrences
        of <em class="parameter"><code>delimiter</code></em> and returns
        the <em class="parameter"><code>n</code></em>'th field (counting from one).
       </p>
       <p>
        <code class="literal">split_part('abc~@~def~@~ghi', '~@~', 2)</code>
        → <code class="returnvalue">def</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.32.1.1.1" class="indexterm"></a>
        <code class="function">strpos</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>substring</code></em> <code class="type">text</code> )
        → <code class="returnvalue">integer</code>
       </p>
       <p>
        Returns starting index of specified <em class="parameter"><code>substring</code></em>
        within <em class="parameter"><code>string</code></em>, or zero if it's not present.
        (Same as <code class="literal">position(<em class="parameter"><code>substring</code></em> in
        <em class="parameter"><code>string</code></em>)</code>, but note the reversed
        argument order.)
       </p>
       <p>
        <code class="literal">strpos('high', 'ig')</code>
        → <code class="returnvalue">2</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.33.1.1.1" class="indexterm"></a>
        <code class="function">substr</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>start</code></em> <code class="type">integer</code> [<span class="optional">, <em class="parameter"><code>count</code></em> <code class="type">integer</code> </span>] )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Extracts the substring of <em class="parameter"><code>string</code></em> starting at
        the <em class="parameter"><code>start</code></em>'th character,
        and extending for <em class="parameter"><code>count</code></em> characters if that is
        specified.  (Same
        as <code class="literal">substring(<em class="parameter"><code>string</code></em>
        from <em class="parameter"><code>start</code></em>
        for <em class="parameter"><code>count</code></em>)</code>.)
       </p>
       <p>
        <code class="literal">substr('alphabet', 3)</code>
        → <code class="returnvalue">phabet</code>
       </p>
       <p>
        <code class="literal">substr('alphabet', 3, 2)</code>
        → <code class="returnvalue">ph</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.34.1.1.1" class="indexterm"></a>
        <code class="function">starts_with</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>, <em class="parameter"><code>prefix</code></em> <code class="type">text</code> )
        → <code class="returnvalue">boolean</code>
       </p>
       <p>
        Returns true if <em class="parameter"><code>string</code></em> starts
        with <em class="parameter"><code>prefix</code></em>.
       </p>
       <p>
        <code class="literal">starts_with('alphabet', 'alph')</code>
        → <code class="returnvalue">t</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.35.1.1.1" class="indexterm"></a>
        <code class="function">to_ascii</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p class="func_signature">
        <code class="function">to_ascii</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>encoding</code></em> <code class="type">name</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p class="func_signature">
        <code class="function">to_ascii</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>encoding</code></em> <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts <em class="parameter"><code>string</code></em> to <acronym class="acronym">ASCII</acronym>
        from another encoding, which may be identified by name or number.
        If <em class="parameter"><code>encoding</code></em> is omitted the database encoding
        is assumed (which in practice is the only useful case).
        The conversion consists primarily of dropping accents.
        Conversion is only supported
        from <code class="literal">LATIN1</code>, <code class="literal">LATIN2</code>,
        <code class="literal">LATIN9</code>, and <code class="literal">WIN1250</code> encodings.
        (See the <a class="xref" href="unaccent.html" title="F.43. unaccent">unaccent</a> module for another, more flexible
        solution.)
       </p>
       <p>
        <code class="literal">to_ascii('Karél')</code>
        → <code class="returnvalue">Karel</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.36.1.1.1" class="indexterm"></a>
        <code class="function">to_hex</code> ( <code class="type">integer</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p class="func_signature">
        <code class="function">to_hex</code> ( <code class="type">bigint</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Converts the number to its equivalent hexadecimal representation.
       </p>
       <p>
        <code class="literal">to_hex(2147483647)</code>
        → <code class="returnvalue">7fffffff</code>
       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
        <a id="id-1.5.8.10.7.2.2.37.1.1.1" class="indexterm"></a>
        <code class="function">translate</code> ( <em class="parameter"><code>string</code></em> <code class="type">text</code>,
        <em class="parameter"><code>from</code></em> <code class="type">text</code>,
        <em class="parameter"><code>to</code></em> <code class="type">text</code> )
        → <code class="returnvalue">text</code>
       </p>
       <p>
        Replaces each character in <em class="parameter"><code>string</code></em> that
        matches a character in the <em class="parameter"><code>from</code></em> set with the
        corresponding character in the <em class="parameter"><code>to</code></em>
        set. If <em class="parameter"><code>from</code></em> is longer than
        <em class="parameter"><code>to</code></em>, occurrences of the extra characters in
        <em class="parameter"><code>from</code></em> are deleted.
       </p>
       <p>
        <code class="literal">translate('12345', '143', 'ax')</code>
        → <code class="returnvalue">a2x5</code>
       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
    The <code class="function">concat</code>, <code class="function">concat_ws</code> and
    <code class="function">format</code> functions are variadic, so it is possible to
    pass the values to be concatenated or formatted as an array marked with
    the <code class="literal">VARIADIC</code> keyword (see <a class="xref" href="xfunc-sql.html#XFUNC-SQL-VARIADIC-FUNCTIONS" title="37.5.5. SQL Functions with Variable Numbers of Arguments">Section 37.5.5</a>).  The array's elements are
    treated as if they were separate ordinary arguments to the function.
    If the variadic array argument is NULL, <code class="function">concat</code>
    and <code class="function">concat_ws</code> return NULL, but
    <code class="function">format</code> treats a NULL as a zero-element array.
   </p><p>
    See also the aggregate function <code class="function">string_agg</code> in
    <a class="xref" href="functions-aggregate.html" title="9.21. Aggregate Functions">Section 9.21</a>, and the functions for
    converting between strings and the <code class="type">bytea</code> type in
    <a class="xref" href="functions-binarystring.html#FUNCTIONS-BINARYSTRING-CONVERSIONS" title="Table 9.13. Text/Binary String Conversion Functions">Table 9.13</a>.
   </p><div class="sect2" id="FUNCTIONS-STRING-FORMAT"><div class="titlepage"><div><div><h3 class="title">9.4.1. <code class="function">format</code></h3></div></div></div><a id="id-1.5.8.10.10.2" class="indexterm"></a><p>
     The function <code class="function">format</code> produces output formatted according to
     a format string, in a style similar to the C function
     <code class="function">sprintf</code>.
    </p><p>
</p><pre class="synopsis">
<code class="function">format</code>(<em class="parameter"><code>formatstr</code></em> <code class="type">text</code> [, <em class="parameter"><code>formatarg</code></em> <code class="type">"any"</code> [, ...] ])
</pre><p>
     <em class="parameter"><code>formatstr</code></em> is a format string that specifies how the
     result should be formatted.  Text in the format string is copied
     directly to the result, except where <em class="firstterm">format specifiers</em> are
     used.  Format specifiers act as placeholders in the string, defining how
     subsequent function arguments should be formatted and inserted into the
     result.  Each <em class="parameter"><code>formatarg</code></em> argument is converted to text
     according to the usual output rules for its data type, and then formatted
     and inserted into the result string according to the format specifier(s).
    </p><p>
     Format specifiers are introduced by a <code class="literal">%</code> character and have
     the form
</p><pre class="synopsis">
%[<em class="parameter"><code>position</code></em>][<em class="parameter"><code>flags</code></em>][<em class="parameter"><code>width</code></em>]<em class="parameter"><code>type</code></em>
</pre><p>
     where the component fields are:

     </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>position</code></em> (optional)</span></dt><dd><p>
         A string of the form <code class="literal"><em class="parameter"><code>n</code></em>$</code> where
         <em class="parameter"><code>n</code></em> is the index of the argument to print.
         Index 1 means the first argument after
         <em class="parameter"><code>formatstr</code></em>.  If the <em class="parameter"><code>position</code></em> is
         omitted, the default is to use the next argument in sequence.
        </p></dd><dt><span class="term"><em class="parameter"><code>flags</code></em> (optional)</span></dt><dd><p>
         Additional options controlling how the format specifier's output is
         formatted.  Currently the only supported flag is a minus sign
         (<code class="literal">-</code>) which will cause the format specifier's output to be
         left-justified.  This has no effect unless the <em class="parameter"><code>width</code></em>
         field is also specified.
        </p></dd><dt><span class="term"><em class="parameter"><code>width</code></em> (optional)</span></dt><dd><p>
         Specifies the <span class="emphasis"><em>minimum</em></span> number of characters to use to
         display the format specifier's output.  The output is padded on the
         left or right (depending on the <code class="literal">-</code> flag) with spaces as
         needed to fill the width.  A too-small width does not cause
         truncation of the output, but is simply ignored.  The width may be
         specified using any of the following: a positive integer; an
         asterisk (<code class="literal">*</code>) to use the next function argument as the
         width; or a string of the form <code class="literal">*<em class="parameter"><code>n</code></em>$</code> to
         use the <em class="parameter"><code>n</code></em>th function argument as the width.
        </p><p>
         If the width comes from a function argument, that argument is
         consumed before the argument that is used for the format specifier's
         value.  If the width argument is negative, the result is left
         aligned (as if the <code class="literal">-</code> flag had been specified) within a
         field of length <code class="function">abs</code>(<em class="parameter"><code>width</code></em>).
        </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em> (required)</span></dt><dd><p>
         The type of format conversion to use to produce the format
         specifier's output.  The following types are supported:
         </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
            <code class="literal">s</code> formats the argument value as a simple
            string.  A null value is treated as an empty string.
           </p></li><li class="listitem"><p>
            <code class="literal">I</code> treats the argument value as an SQL
            identifier, double-quoting it if necessary.
            It is an error for the value to be null (equivalent to
            <code class="function">quote_ident</code>).
           </p></li><li class="listitem"><p>
            <code class="literal">L</code> quotes the argument value as an SQL literal.
            A null value is displayed as the string <code class="literal">NULL</code>, without
            quotes (equivalent to <code class="function">quote_nullable</code>).
           </p></li></ul></div><p>
        </p></dd></dl></div><p>
    </p><p>
     In addition to the format specifiers described above, the special sequence
     <code class="literal">%%</code> may be used to output a literal <code class="literal">%</code> character.
    </p><p>
     Here are some examples of the basic format conversions:

</p><pre class="screen">
SELECT format('Hello %s', 'World');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">Hello World</code>

SELECT format('Testing %s, %s, %s, %%', 'one', 'two', 'three');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">Testing one, two, three, %</code>

SELECT format('INSERT INTO %I VALUES(%L)', 'Foo bar', E'O\'Reilly');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">INSERT INTO "Foo bar" VALUES('O''Reilly')</code>

SELECT format('INSERT INTO %I VALUES(%L)', 'locations', 'C:\Program Files');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">INSERT INTO locations VALUES('C:\Program Files')</code>
</pre><p>
    </p><p>
     Here are examples using <em class="parameter"><code>width</code></em> fields
     and the <code class="literal">-</code> flag:

</p><pre class="screen">
SELECT format('|%10s|', 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|       foo|</code>

SELECT format('|%-10s|', 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|foo       |</code>

SELECT format('|%*s|', 10, 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|       foo|</code>

SELECT format('|%*s|', -10, 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|foo       |</code>

SELECT format('|%-*s|', 10, 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|foo       |</code>

SELECT format('|%-*s|', -10, 'foo');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|foo       |</code>
</pre><p>
    </p><p>
     These examples show use of <em class="parameter"><code>position</code></em> fields:

</p><pre class="screen">
SELECT format('Testing %3$s, %2$s, %1$s', 'one', 'two', 'three');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">Testing three, two, one</code>

SELECT format('|%*2$s|', 'foo', 10, 'bar');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|       bar|</code>

SELECT format('|%1$*2$s|', 'foo', 10, 'bar');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">|       foo|</code>
</pre><p>
    </p><p>
     Unlike the standard C function <code class="function">sprintf</code>,
     <span class="productname">PostgreSQL</span>'s <code class="function">format</code> function allows format
     specifiers with and without <em class="parameter"><code>position</code></em> fields to be mixed
     in the same format string.  A format specifier without a
     <em class="parameter"><code>position</code></em> field always uses the next argument after the
     last argument consumed.
     In addition, the <code class="function">format</code> function does not require all
     function arguments to be used in the format string.
     For example:

</p><pre class="screen">
SELECT format('Testing %3$s, %2$s, %s', 'one', 'two', 'three');
<em class="lineannotation"><span class="lineannotation">Result: </span></em><code class="computeroutput">Testing three, two, three</code>
</pre><p>
    </p><p>
     The <code class="literal">%I</code> and <code class="literal">%L</code> format specifiers are particularly
     useful for safely constructing dynamic SQL statements.  See
     <a class="xref" href="plpgsql-statements.html#PLPGSQL-QUOTE-LITERAL-EXAMPLE" title="Example 42.1. Quoting Values in Dynamic Queries">Example 42.1</a>.
    </p></div></div><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navfooter"><hr></hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="functions-math.html" title="9.3. Mathematical Functions and Operators">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="functions-binarystring.html" title="9.5. Binary String Functions and Operators">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9.3. Mathematical Functions and Operators </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 13.1 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 9.5. Binary String Functions and Operators</td></tr></table></div></body></html>