func.sgml

PostgreSQL7.4.6 for Linux

      <row>
       <entry><literal><function>md5</function>(<parameter>string</parameter> <type>text</type>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>
        Calculates the MD5 hash of given string, returning the result in hexadecimal.
       </entry>
       <entry><literal>md5('abc')</literal></entry>
       <entry><literal>900150983cd24fb0 d6963f7d28e17f72</literal></entry>
      </row>

      <row>
       <entry><literal><function>pg_client_encoding</function>()</literal></entry>
       <entry><type>name</type></entry>
       <entry>
        Current client encoding name
       </entry>
       <entry><literal>pg_client_encoding()</literal></entry>
       <entry><literal>SQL_ASCII</literal></entry>
      </row>

      <row>
       <entry><literal><function>quote_ident</function>(<parameter>string</parameter> text)</literal><indexterm><primary>quote_ident</></></entry>
       <entry><type>text</type></entry>
       <entry>
        Return the given string suitably quoted to be used as an identifier
	in an <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.
       </entry>
       <entry><literal>quote_ident('Foo')</literal></entry>
       <entry><literal>"Foo"</literal></entry>
      </row>

      <row>
       <entry><literal><function>quote_literal</function>(<parameter>string</parameter> text)</literal><indexterm><primary>quote_literal</></></entry>
       <entry><type>text</type></entry>
       <entry>
        Return the given string suitably quoted to be used as a string literal
	in an <acronym>SQL</acronym> statement string.
	Embedded quotes and backslashes are properly doubled.
       </entry>
       <entry><literal>quote_literal( 'O\'Reilly')</literal></entry>
       <entry><literal>'O''Reilly'</literal></entry>
      </row>

      <row>
       <entry><literal><function>repeat</function>(<type>text</type>, <type>integer</type>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>Repeat text a number of times</entry>
       <entry><literal>repeat('Pg', 4)</literal></entry>
       <entry><literal>PgPgPgPg</literal></entry>
      </row>

      <row>
       <entry><literal><function>replace</function>(<parameter>string</parameter> <type>text</type>,
       <parameter>from</parameter> <type>text</type>,
       <parameter>to</parameter> <type>text</type>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>Replace all occurrences in <parameter>string</parameter> of substring
        <parameter>from</parameter> with substring <parameter>to</parameter>.
       </entry>
       <entry><literal>replace( 'abcdefabcdef', 'cd', 'XX')</literal></entry>
       <entry><literal>abXXefabXXef</literal></entry>
      </row>

      <row>
       <entry>
        <literal><function>rpad</function>(<parameter>string</parameter> <type>text</type>,
        <parameter>length</parameter> <type>integer</type>
        <optional>, <parameter>fill</parameter> <type>text</type></optional>)</literal>
       </entry>
       <entry><type>text</type></entry>
       <entry>
        Fill up the <parameter>string</parameter> to length
        <parameter>length</parameter> by appending the characters
        <parameter>fill</parameter> (a space by default).  If the
        <parameter>string</parameter> is already longer than
        <parameter>length</parameter> then it is truncated.
       </entry>
       <entry><literal>rpad('hi', 5, 'xy')</literal></entry>
       <entry><literal>hixyx</literal></entry>
      </row>

      <row>
       <entry><literal><function>rtrim</function>(<parameter>string</parameter>
        text, <parameter>characters</parameter> text)</literal></entry>
       <entry><type>text</type></entry>
       <entry>
        Remove the longest string containing only characters from
        <parameter>characters</parameter> from the end of the string.
       </entry>
       <entry><literal>rtrim('trimxxxx', 'x')</literal></entry>
       <entry><literal>trim</literal></entry>
      </row>

      <row>
       <entry><literal><function>split_part</function>(<parameter>string</parameter> <type>text</type>,
       <parameter>delimiter</parameter> <type>text</type>,
       <parameter>field</parameter> <type>integer</type>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>Split <parameter>string</parameter> on <parameter>delimiter</parameter>
        and return the given field (counting from one)
       </entry>
       <entry><literal>split_part( 'abc~@~def~@~ghi', '~@~', 2)</literal></entry>
       <entry><literal>def</literal></entry>
      </row>

      <row>
       <entry><literal><function>strpos</function>(<parameter>string</parameter>, <parameter>substring</parameter>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>
        Location of specified substring (same as
        <literal>position(<parameter>substring</parameter> in
         <parameter>string</parameter>)</literal>, but note the reversed
        argument order)
       </entry>
       <entry><literal>strpos('high', 'ig')</literal></entry>
       <entry><literal>2</literal></entry>
      </row>

      <row>
       <entry><literal><function>substr</function>(<parameter>string</parameter>, <parameter>from</parameter> <optional>, <parameter>count</parameter></optional>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>
        Extract substring (same as
        <literal>substring(<parameter>string</parameter> from <parameter>from</parameter> for <parameter>count</parameter>)</literal>)
       </entry>
       <entry><literal>substr('alphabet', 3, 2)</literal></entry>
       <entry><literal>ph</literal></entry>
      </row>

      <row>
       <entry><literal><function>to_ascii</function>(<type>text</type>
        <optional>, <parameter>encoding</parameter></optional>)</literal></entry>
       <entry><type>text</type></entry>

       <entry>
       Convert text to <acronym>ASCII</acronym> from other encoding
       <footnote>
        <para>
         The <function>to_ascii</function> function supports conversion from
         <literal>LATIN1</>, <literal>LATIN2</>, and <literal>WIN1250</> only.
        </para>
       </footnote>
       </entry>

       <entry><literal>to_ascii('Karel')</literal></entry>
       <entry><literal>Karel</literal></entry>
      </row>

      <row>
       <entry><literal><function>to_hex</function>(<parameter>number</parameter> <type>integer</type>
       or <type>bigint</type>)</literal></entry>
       <entry><type>text</type></entry>
       <entry>Convert <parameter>number</parameter> to its equivalent hexadecimal
        representation
       </entry>
       <entry><literal>to_hex(2147483647)</literal></entry>
       <entry><literal>7fffffff</literal></entry>
      </row>

      <row>
       <entry>
        <literal><function>translate</function>(<parameter>string</parameter>
        <type>text</type>,
        <parameter>from</parameter> <type>text</type>,
        <parameter>to</parameter> <type>text</type>)</literal>
       </entry>
       <entry><type>text</type></entry>
       <entry>
        Any character in <parameter>string</parameter> that matches a
        character in the <parameter>from</parameter> set is replaced by
        the corresponding character in the <parameter>to</parameter>
        set.
       </entry>
       <entry><literal>translate('12345', '14', 'ax')</literal></entry>
       <entry><literal>a23x5</literal></entry>
      </row>       
      
     </tbody>
    </tgroup>
   </table>


   <table id="conversion-names">
    <title>Built-in Conversions</title>
    <tgroup cols="3">
     <thead>
      <row>
       <entry>Conversion Name
        <footnote>
         <para>
          The conversion names follow a standard naming scheme: The
          official name of the source encoding with all
          non-alphanumeric characters replaced by underscores followed
          by <literal>_to_</literal> followed by the equally processed
          destination encoding name. Therefore the names might deviate
          from the customary encoding names.
         </para>
        </footnote>
       </entry>
       <entry>Source Encoding</entry>
       <entry>Destination Encoding</entry>
      </row>
     </thead>

     <tbody>
      <row>
       <entry><literal>ascii_to_mic</literal></entry>
       <entry><literal>SQL_ASCII</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>ascii_to_utf_8</literal></entry>
       <entry><literal>SQL_ASCII</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>big5_to_euc_tw</literal></entry>
       <entry><literal>BIG5</literal></entry>
       <entry><literal>EUC_TW</literal></entry>
      </row>

      <row>
       <entry><literal>big5_to_mic</literal></entry>
       <entry><literal>BIG5</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>big5_to_utf_8</literal></entry>
       <entry><literal>BIG5</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>euc_cn_to_mic</literal></entry>
       <entry><literal>EUC_CN</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>euc_cn_to_utf_8</literal></entry>
       <entry><literal>EUC_CN</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>euc_jp_to_mic</literal></entry>
       <entry><literal>EUC_JP</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>euc_jp_to_sjis</literal></entry>
       <entry><literal>EUC_JP</literal></entry>
       <entry><literal>SJIS</literal></entry>
      </row>

      <row>
       <entry><literal>euc_jp_to_utf_8</literal></entry>
       <entry><literal>EUC_JP</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>euc_kr_to_mic</literal></entry>
       <entry><literal>EUC_KR</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>euc_kr_to_utf_8</literal></entry>
       <entry><literal>EUC_KR</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>euc_tw_to_big5</literal></entry>
       <entry><literal>EUC_TW</literal></entry>
       <entry><literal>BIG5</literal></entry>
      </row>

      <row>
       <entry><literal>euc_tw_to_mic</literal></entry>
       <entry><literal>EUC_TW</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>euc_tw_to_utf_8</literal></entry>
       <entry><literal>EUC_TW</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>gb18030_to_utf_8</literal></entry>
       <entry><literal>GB18030</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>gbk_to_utf_8</literal></entry>
       <entry><literal>GBK</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_10_to_utf_8</literal></entry>
       <entry><literal>LATIN6</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_13_to_utf_8</literal></entry>
       <entry><literal>LATIN7</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_14_to_utf_8</literal></entry>
       <entry><literal>LATIN8</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_15_to_utf_8</literal></entry>
       <entry><literal>LATIN9</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_16_to_utf_8</literal></entry>
       <entry><literal>LATIN10</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_1_to_mic</literal></entry>
       <entry><literal>LATIN1</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_1_to_utf_8</literal></entry>
       <entry><literal>LATIN1</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_2_to_mic</literal></entry>
       <entry><literal>LATIN2</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_2_to_utf_8</literal></entry>
       <entry><literal>LATIN2</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_2_to_windows_1250</literal></entry>
       <entry><literal>LATIN2</literal></entry>
       <entry><literal>WIN1250</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_3_to_mic</literal></entry>
       <entry><literal>LATIN3</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_3_to_utf_8</literal></entry>
       <entry><literal>LATIN3</literal></entry>
       <entry><literal>UNICODE</literal></entry>
      </row>

      <row>
       <entry><literal>iso_8859_4_to_mic</literal></entry>
       <entry><literal>LATIN4</literal></entry>
       <entry><literal>MULE_INTERNAL</literal></entry>
      </row>