<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/libpgeasy.sgml,v 2.9 2002/03/04 18:50:20 momjian Exp $
-->

 <chapter id="pgeasy">
  <title><application>libpgeasy</application> - Simplified C Library</title>

  <note>
   <title>Author</title>

   <para>
    Written by Bruce Momjian
    (<email>pgman@candle.pha.pa.us</email>)
    and last updated 2002-03-04
   </para>
  </note>

  <para>
   <application>pgeasy</application> allows you to cleanly interface
   to the <application>libpq</application> library, more like a 4GL
   SQL interface.  Refer to <xref linkend="libpq"> for more
   information about <application>libpq</application>.
  </para>

  <para>
   It consists of a set of simplified C functions that encapsulate the
   functionality of <application>libpq</application>. The functions are:

   <itemizedlist>
    <listitem>
<synopsis>
PGresult   *doquery(char *query);
</synopsis>
    </listitem>

    <listitem>
<synopsis>
PGconn     *connectdb(char *options);
</synopsis>
    </listitem>

    <listitem>
<synopsis>
void        disconnectdb();
</synopsis>
    </listitem>

    <listitem>
<synopsis>
int         fetch(void *param,...);
</synopsis>
    </listitem>

    <listitem>
<synopsis>
int         fetchwithnulls(void *param,...);
</synopsis>
    </listitem>

    <listitem>
<synopsis>
void        reset_fetch();
</synopsis>
    </listitem>

    <listitem>
<synopsis>
void        on_error_continue();
</synopsis>
    </listitem>

    <listitem>
<synopsis>
void        on_error_stop();
</synopsis>
    </listitem>

    <listitem>
<synopsis>
PGresult   *get_result();
</synopsis>
    </listitem>

    <listitem>
<synopsis>
void        set_result(PGresult *newres);
</synopsis>
    </listitem>

   </itemizedlist>
  </para>

  <para>
   Many functions return a structure or value, so you can work
   with the result if required.
  </para>

  <para>
   You basically connect to the database with
   <function>connectdb</function>, issue your query with
   <function>doquery</function>, fetch the results with
   <function>fetch</function>, and finish with
   <function>disconnectdb</function>.
  </para>

  <para>
   For <literal>SELECT</literal> queries, <function>fetch</function>
   allows you to pass pointers as parameters, and on return the
   variables are filled with data from the binary cursor you opened.
   These binary cursors cannot be used if you are running the
   <application>pgeasy</application> client on a system with a different
   architecture than the database server. If you pass a NULL pointer
   parameter, the column is skipped. <function>fetchwithnulls</function>
   allows you to retrieve the NULL status of the field by passing an
   <literal>int*</literal> after each result pointer, which returns true
   or false to indicate if the field is null. You can always use
   <application>libpq</application> functions on the
   <structname>PGresult</structname> pointer returned by
   <function>doquery</function>. <function>reset_fetch</function> starts
   the fetch back at the beginning.
  </para>

  <para>
   <function>get_result</function> and <function>set_result</function>
   allow you to handle multiple open result sets. Use
   <function>get_result</function> to save a result into an application
   variable. You can then later use <function>set_result</function> to
   return to the previously save result.
  </para>

  <para>
   There are several demonstration programs in
   <filename>pgsql/src/interfaces/libpgeasy/examples</>.
  </para>
 </chapter>

<!-- Keep this comment at the end of the file
Local variables:
mode:sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"./reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:("/usr/lib/sgml/catalog")
sgml-local-ecat-files:nil
End:
-->
