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<?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>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 Vsnapshot" /><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 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 16.3 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 /></div><div class="sect1" id="FUNCTIONS-STRING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9.4. String Functions and Operators <a href="#FUNCTIONS-STRING" class="id_link">#</a></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 and Operators">Table 9.10</a>).
</p><div class="note"><h3 class="title">Note</h3><p>
The string concatenation operator (<code class="literal">||</code>) will accept
non-string input, so long as at least one input is of 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, inserting an
explicit coercion to <code class="type">text</code> can be used to have non-string input
accepted.
</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>
<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-1.5.8.10.5.2.2.4.1.1.1" class="indexterm"></a>
<a id="id-1.5.8.10.5.2.2.4.1.1.2" 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&'\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-1.5.8.10.5.2.2.5.1.1.1" 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-1.5.8.10.5.2.2.6.1.1.1" class="indexterm"></a>
<a id="id-1.5.8.10.5.2.2.6.1.1.2" class="indexterm"></a>
<a id="id-1.5.8.10.5.2.2.6.1.1.3" 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-1.5.8.10.5.2.2.6.1.2.1" 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-1.5.8.10.5.2.2.7.1.1.1" 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-1.5.8.10.5.2.2.8.1.1.1" 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-1.5.8.10.5.2.2.9.1.1.1" 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-1.5.8.10.5.2.2.10.1.1.1" class="indexterm"></a>
<a id="id-1.5.8.10.5.2.2.10.1.1.2" 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&'\0061\0308bc', NFC)</code>
→ <code class="returnvalue">U&'\00E4bc'</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.5.2.2.11.1.1.1" 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-1.5.8.10.5.2.2.12.1.1.1" 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-1.5.8.10.5.2.2.13.1.1.1" 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-1.5.8.10.5.2.2.14.1.1.1" 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 first starting index of the 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-1.5.8.10.5.2.2.15.1.1.1" 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="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-1.5.8.10.5.2.2.16.1.1.1" 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-1.5.8.10.5.2.2.17.1.1.1" 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 the first 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">SIMILAR</code> <em class="parameter"><code>pattern</code></em> <code class="type">text</code> <code class="literal">ESCAPE</code> <em class="parameter"><code>escape</code></em> <code class="type">text</code> )
→ <code class="returnvalue">text</code>
</p>
<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 the first 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>. The first form has
been specified since SQL:2003; the second form was only in SQL:1999
and should be considered obsolete.
</p>
<p>
<code class="literal">substring('Thomas' similar '%#"o_a#"_' escape '#')</code>
→ <code class="returnvalue">oma</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.5.2.2.20.1.1.1" 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-1.5.8.10.5.2.2.22.1.1.1" 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 and operators are available
and are listed in <a class="xref" href="functions-string.html#FUNCTIONS-STRING-OTHER" title="Table 9.10. Other String Functions and Operators">Table 9.10</a>. (Some of
these 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>.)
There are also pattern-matching operators, which are described in
<a class="xref" href="functions-matching.html" title="9.7. Pattern Matching">Section 9.7</a>, and operators for full-text
search, which are described in <a class="xref" href="textsearch.html" title="Chapter 12. Full Text Search">Chapter 12</a>.
</p><div class="table" id="FUNCTIONS-STRING-OTHER"><p class="title"><strong>Table 9.10. Other String Functions and Operators</strong></p><div class="table-contents"><table class="table" summary="Other 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-1.5.8.10.7.2.2.1.1.1.1" class="indexterm"></a>
<code class="type">text</code> <code class="literal">^@</code> <code class="type">text</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Returns true if the first string starts with the second string
(equivalent to the <code class="function">starts_with()</code> function).
</p>
<p>
<code class="literal">'alphabet' ^@ 'alph'</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.7.2.2.2.1.1.1" 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-1.5.8.10.7.2.2.3.1.1.1" 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">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-1.5.8.10.7.2.2.11.1.1.1" 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-1.5.8.10.7.2.2.12.1.1.1" 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-1.5.8.10.7.2.2.13.1.1.1" 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 43.1. Quoting Values in Dynamic Queries">Example 43.1</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-1.5.8.10.7.2.2.14.1.1.1" 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 43.1. Quoting Values in Dynamic Queries">Example 43.1</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-1.5.8.10.7.2.2.16.1.1.1" 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 43.1. Quoting Values in Dynamic Queries">Example 43.1</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-1.5.8.10.7.2.2.18.1.1.1" class="indexterm"></a>
<code class="function">regexp_count</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>start</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] ] )
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns the number of times the POSIX regular
expression <em class="parameter"><code>pattern</code></em> matches in
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_count('123456789012', '\d\d\d', 2)</code>
→ <code class="returnvalue">3</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.7.2.2.19.1.1.1" class="indexterm"></a>
<code class="function">regexp_instr</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>start</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>N</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>endoption</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>flags</code></em> <code class="type">text</code>
[, <em class="parameter"><code>subexpr</code></em> <code class="type">integer</code> ] ] ] ] ] )
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns the position within <em class="parameter"><code>string</code></em> where
the <em class="parameter"><code>N</code></em>'th match of the POSIX regular
expression <em class="parameter"><code>pattern</code></em> occurs, or zero if there is
no such match; 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_instr('ABCDEF', 'c(.)(..)', 1, 1, 0, 'i')</code>
→ <code class="returnvalue">3</code>
</p>
<p>
<code class="literal">regexp_instr('ABCDEF', 'c(.)(..)', 1, 1, 0, 'i', 2)</code>
→ <code class="returnvalue">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_like</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">boolean</code>
</p>
<p>
Checks whether a match of the POSIX regular
expression <em class="parameter"><code>pattern</code></em> occurs
within <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_like('Hello World', 'world$', 'i')</code>
→ <code class="returnvalue">t</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.7.2.2.21.1.1.1" 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 substrings within the first match of the POSIX regular
expression <em class="parameter"><code>pattern</code></em> 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-1.5.8.10.7.2.2.22.1.1.1" 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 substrings within the first match of the POSIX regular
expression <em class="parameter"><code>pattern</code></em> to
the <em class="parameter"><code>string</code></em>, or substrings within all
such matches if the <code class="literal">g</code> flag is used;
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-1.5.8.10.7.2.2.23.1.1.1" 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>start</code></em> <code class="type">integer</code> ]
[, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
→ <code class="returnvalue">text</code>
</p>
<p>
Replaces the substring that is the first match to the POSIX
regular expression <em class="parameter"><code>pattern</code></em>, or all such
matches if the <code class="literal">g</code> flag is used; 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">
<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>start</code></em> <code class="type">integer</code>,
<em class="parameter"><code>N</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>flags</code></em> <code class="type">text</code> ] )
→ <code class="returnvalue">text</code>
</p>
<p>
Replaces the substring that is the <em class="parameter"><code>N</code></em>'th
match to the POSIX regular expression <em class="parameter"><code>pattern</code></em>,
or all such matches if <em class="parameter"><code>N</code></em> is zero; 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', '.', 'X', 3, 2)</code>
→ <code class="returnvalue">ThoXas</code>
</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">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, producing an array of results; 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-1.5.8.10.7.2.2.26.1.1.1" 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, producing a set of results; 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-1.5.8.10.7.2.2.27.1.1.1" class="indexterm"></a>
<code class="function">regexp_substr</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>start</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>N</code></em> <code class="type">integer</code>
[, <em class="parameter"><code>flags</code></em> <code class="type">text</code>
[, <em class="parameter"><code>subexpr</code></em> <code class="type">integer</code> ] ] ] ] )
→ <code class="returnvalue">text</code>
</p>
<p>
Returns the substring within <em class="parameter"><code>string</code></em> that
matches the <em class="parameter"><code>N</code></em>'th occurrence of the POSIX
regular expression <em class="parameter"><code>pattern</code></em>,
or <code class="literal">NULL</code> if there is no such match; 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_substr('ABCDEF', 'c(.)(..)', 1, 1, 'i')</code>
→ <code class="returnvalue">CDEF</code>
</p>
<p>
<code class="literal">regexp_substr('ABCDEF', 'c(.)(..)', 1, 1, 'i', 2)</code>
→ <code class="returnvalue">EF</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">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-1.5.8.10.7.2.2.29.1.1.1" 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-1.5.8.10.7.2.2.30.1.1.1" 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-1.5.8.10.7.2.2.31.1.1.1" 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="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-1.5.8.10.7.2.2.32.1.1.1" 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),
or when <em class="parameter"><code>n</code></em> is negative, returns
the |<em class="parameter"><code>n</code></em>|'th-from-last field.
</p>
<p>
<code class="literal">split_part('abc~@~def~@~ghi', '~@~', 2)</code>
→ <code class="returnvalue">def</code>
</p>
<p>
<code class="literal">split_part('abc,def,ghi,jkl', ',', -2)</code>
→ <code class="returnvalue">ghi</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">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="FUNCTION-STRING-TO-ARRAY" class="indexterm"></a>
<code class="function">string_to_array</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> [<span class="optional">, <em class="parameter"><code>null_string</code></em> <code class="type">text</code> </span>] )
→ <code class="returnvalue">text[]</code>
</p>
<p>
Splits the <em class="parameter"><code>string</code></em> at occurrences
of <em class="parameter"><code>delimiter</code></em> and forms the resulting fields
into a <code class="type">text</code> array.
If <em class="parameter"><code>delimiter</code></em> is <code class="literal">NULL</code>,
each character in the <em class="parameter"><code>string</code></em> will become a
separate element in the array.
If <em class="parameter"><code>delimiter</code></em> is an empty string, then
the <em class="parameter"><code>string</code></em> is treated as a single field.
If <em class="parameter"><code>null_string</code></em> is supplied and is
not <code class="literal">NULL</code>, fields matching that string are
replaced by <code class="literal">NULL</code>.
See also <a class="link" href="functions-array.html#FUNCTION-ARRAY-TO-STRING"><code class="function">array_to_string</code></a>.
</p>
<p>
<code class="literal">string_to_array('xx~~yy~~zz', '~~', 'yy')</code>
→ <code class="returnvalue">{xx,NULL,zz}</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">string_to_table</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> [<span class="optional">, <em class="parameter"><code>null_string</code></em> <code class="type">text</code> </span>] )
→ <code class="returnvalue">setof text</code>
</p>
<p>
Splits the <em class="parameter"><code>string</code></em> at occurrences
of <em class="parameter"><code>delimiter</code></em> and returns the resulting fields
as a set of <code class="type">text</code> rows.
If <em class="parameter"><code>delimiter</code></em> is <code class="literal">NULL</code>,
each character in the <em class="parameter"><code>string</code></em> will become a
separate row of the result.
If <em class="parameter"><code>delimiter</code></em> is an empty string, then
the <em class="parameter"><code>string</code></em> is treated as a single field.
If <em class="parameter"><code>null_string</code></em> is supplied and is
not <code class="literal">NULL</code>, fields matching that string are
replaced by <code class="literal">NULL</code>.
</p>
<p>
<code class="literal">string_to_table('xx~^~yy~^~zz', '~^~', 'yy')</code>
→ <code class="returnvalue"></code>
</p><pre class="programlisting">
xx
NULL
zz
</pre><p>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.7.2.2.36.1.1.1" 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 first starting index of the 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-1.5.8.10.7.2.2.37.1.1.1" 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-1.5.8.10.7.2.2.38.1.1.1" 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.48. unaccent — a text search dictionary which removes diacritics">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-1.5.8.10.7.2.2.39.1.1.1" 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-1.5.8.10.7.2.2.40.1.1.1" 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><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.5.8.10.7.2.2.41.1.1.1" class="indexterm"></a>
<code class="function">unistr</code> ( <code class="type">text</code> )
→ <code class="returnvalue">text</code>
</p>
<p>
Evaluate escaped Unicode characters in the argument. Unicode characters
can be specified as
<code class="literal">\<em class="replaceable"><code>XXXX</code></em></code> (4 hexadecimal
digits), <code class="literal">\+<em class="replaceable"><code>XXXXXX</code></em></code> (6
hexadecimal digits),
<code class="literal">\u<em class="replaceable"><code>XXXX</code></em></code> (4 hexadecimal
digits), or <code class="literal">\U<em class="replaceable"><code>XXXXXXXX</code></em></code>
(8 hexadecimal digits). To specify a backslash, write two
backslashes. All other characters are taken literally.
</p>
<p>
If the server encoding is not UTF-8, the Unicode code point identified
by one of these escape sequences is converted to the actual server
encoding; an error is reported if that's not possible.
</p>
<p>
This function provides a (non-standard) alternative to string
constants with Unicode escapes (see <a class="xref" href="sql-syntax-lexical.html#SQL-SYNTAX-STRINGS-UESCAPE" title="4.1.2.3. String Constants with Unicode Escapes">Section 4.1.2.3</a>).
</p>
<p>
<code class="literal">unistr('d\0061t\+000061')</code>
→ <code class="returnvalue">data</code>
</p>
<p>
<code class="literal">unistr('d\u0061t\U00000061')</code>
→ <code class="returnvalue">data</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="38.5.6. SQL Functions with Variable Numbers of Arguments">Section 38.5.6</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> <a href="#FUNCTIONS-STRING-FORMAT" class="id_link">#</a></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 43.1. Quoting Values in Dynamic Queries">Example 43.1</a>.
</p></div></div><div class="navfooter"><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 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 9.5. Binary String Functions and Operators</td></tr></table></div></body></html>
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