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11th chunk of `doc/src/sgml/plperl.sgml`
ad0247b4e08038da236a843c0c0a73e1ad2a7766aaba5a5c0000000100000fa2
 <para>
        Return the given string suitably quoted to be used as an identifier in
        an SQL 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.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>decode_bytea(<replaceable>string</replaceable>)</function></literal>
      <indexterm>
       <primary>decode_bytea</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <listitem>
      <para>
        Return the unescaped binary data represented by the contents of the given string,
        which should be <type>bytea</type> encoded.
        </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>encode_bytea(<replaceable>string</replaceable>)</function></literal>
      <indexterm>
       <primary>encode_bytea</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <listitem>
      <para>
        Return the <type>bytea</type> encoded form of the binary data contents of the given string.
        </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>encode_array_literal(<replaceable>array</replaceable>)</function></literal>
      <indexterm>
       <primary>encode_array_literal</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <term>
      <literal><function>encode_array_literal(<replaceable>array</replaceable>, <replaceable>delimiter</replaceable>)</function></literal>
     </term>
     <listitem>
      <para>
        Returns the contents of the referenced array as a string in array literal format
        (see <xref linkend="arrays-input"/>).
        Returns the argument value unaltered if it's not a reference to an array.
        The delimiter used between elements of the array literal defaults to "<literal>, </literal>"
        if a delimiter is not specified or is undef.
        </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>encode_typed_literal(<replaceable>value</replaceable>, <replaceable>typename</replaceable>)</function></literal>
      <indexterm>
       <primary>encode_typed_literal</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
      <listitem>
       <para>
         Converts a Perl variable to the value of the data type passed as a
         second argument and returns a string representation of this value.
         Correctly handles nested arrays and values of composite types.
       </para>
      </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>encode_array_constructor(<replaceable>array</replaceable>)</function></literal>
      <indexterm>
       <primary>encode_array_constructor</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <listitem>
      <para>
        Returns the contents of the referenced array as a string in array constructor format
        (see <xref linkend="sql-syntax-array-constructors"/>).
        Individual values are quoted using <function>quote_nullable</function>.
        Returns the argument value, quoted using <function>quote_nullable</function>,
        if it's not a reference to an array.
        </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>looks_like_number(<replaceable>string</replaceable>)</function></literal>
      <indexterm>
       <primary>looks_like_number</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <listitem>
      <para>
        Returns a true value if the content of the given string looks like a
        number, according to Perl, returns false otherwise.
        Returns undef if the argument is undef.  Leading and trailing space is
Title: PL/Perl Utility Functions for Data Encoding and Type Checking
Summary
This section describes several PL/Perl utility functions for data encoding and type checking in PostgreSQL. These include encode_bytea() for encoding binary data, encode_array_literal() for converting arrays to string literals, encode_typed_literal() for converting Perl variables to specific PostgreSQL data types, encode_array_constructor() for creating array constructor strings, and looks_like_number() for checking if a string resembles a number. These functions provide essential tools for PL/Perl developers to handle data conversion, formatting, and validation tasks when working with PostgreSQL databases.