might give the wrong results</emphasis>.  Also, it has no way
      to report error conditions.
     </para>

     <para>
      <xref linkend="libpq-PQescapeString"/> can be used safely in
      client programs that work with only one <productname>PostgreSQL</productname>
      connection at a time (in this case it can find out what it needs to
      know <quote>behind the scenes</quote>).  In other contexts it is a security
      hazard and should be avoided in favor of
      <xref linkend="libpq-PQescapeStringConn"/>.
     </para>
     </listitem>
    </varlistentry>

    <varlistentry id="libpq-PQescapeByteaConn">
     <term><function>PQescapeByteaConn</function><indexterm><primary>PQescapeByteaConn</primary></indexterm></term>

     <listitem>
     <para>
       Escapes binary data for use within an SQL command with the type
       <type>bytea</type>.  As with <xref linkend="libpq-PQescapeStringConn"/>,
       this is only used when inserting data directly into an SQL command string.
<synopsis>
unsigned char *PQescapeByteaConn(PGconn *conn,
                                 const unsigned char *from,
                                 size_t from_length,
                                 size_t *to_length);
</synopsis>
      </para>

      <para>
       Certain byte values must be escaped when used as part of a
       <type>bytea</type> literal in an <acronym>SQL</acronym> statement.
       <xref linkend="libpq-PQescapeByteaConn"/> escapes bytes using
       either hex encoding or backslash escaping.  See <xref
       linkend="datatype-binary"/> for more information.
      </para>

      <para>
       The <parameter>from</parameter> parameter points to the first
       byte of the string that is to be escaped, and the
       <parameter>from_length</parameter> parameter gives the number of
       bytes in this binary string.  (A terminating zero byte is
       neither necessary nor counted.)  The <parameter>to_length</parameter>
       parameter points to a variable that will hold the resultant
       escaped string length. This result string length includes the terminating
       zero byte of the result.
      </para>

      <para>
       <xref linkend="libpq-PQescapeByteaConn"/> returns an escaped version of the
       <parameter>from</parameter> parameter binary string in memory
       allocated with <function>malloc()</function>.  This memory should be freed using
       <function>PQfreemem()</function> when the result is no longer needed.  The
       return string has all special characters replaced so that they can
       be properly processed by the <productname>PostgreSQL</productname>
       string literal parser, and the <type>bytea</type> input function. A
       terminating zero byte is also added.  The single quotes that must
       surround <productname>PostgreSQL</productname> string literals are
       not part of the result string.
      </para>

      <para>
       On error, a null pointer is returned, and a suitable error message
       is stored in the <parameter>conn</parameter> object.  Currently, the only
       possible error is insufficient memory for the result string.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry id="libpq-PQescapeBytea">
     <term><function>PQescapeBytea</function><indexterm><primary>PQescapeBytea</primary></indexterm></term>

     <listitem>
      <para>
       <xref linkend="libpq-PQescapeBytea"/> is an older, deprecated version of
       <xref linkend="libpq-PQescapeByteaConn"/>.
<synopsis>
unsigned char *PQescapeBytea(const unsigned char *from,
                             size_t from_length,
                             size_t *to_length);
</synopsis>
      </para>

      <para>
       The only difference from <xref linkend="libpq-PQescapeByteaConn"/> is that
       <xref linkend="libpq-PQescapeBytea"/> does not take a <structname>PGconn</structname>
       parameter.  Because of this, <xref linkend="libpq-PQescapeBytea"/> can
       only be used safely