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<?xml version="1.0" encoding="UTF-8"?>
<refentry version="5.0-subset Scilab" xml:id="mysql_ping" xml:lang="en"
xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:ns3="http://www.w3.org/1999/xhtml"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:db="http://docbook.org/ns/docbook">
<refnamediv>
<refname>mysql_ping</refname>
<refpurpose>Checks whether the connection to the server is working.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>result = mysql_ping(mysql)</synopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>Checks whether the connection to the server is working.
If the connection has gone down and auto-reconnect is enabled
an attempt to reconnect is made. If the connection is down
and auto-reconnect is disabled, <literal>mysql_ping</literal>
returns an error.</para>
<para>Auto-reconnect is disabled by default. To enable it, call
<literal>mysql_options</literal> with the MYSQL_OPT_RECONNECT
option.</para>
<para><literal>mysql_ping</literal> can be used by clients that
remain idle for a long while, to check whether the server has
closed the connection and reconnect if necessary.</para>
<para>If <literal>mysql_ping</literal> does cause a reconnect,
there is no explicit indication of it. To determine whether a
reconnect occurs, call <literal>mysql_thread_id()</literal> to
get the original connection identifier before calling
<literal>mysql_ping</literal>, and then call
<literal>mysql_thread_id</literal> again to see whether
the identifier has changed.</para>
<para>If reconnect occurs, some characteristics of the
connection will have been reset. </para>
</refsection>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term>mysql</term>
<listitem>
<para>a MySQL pointer</para>
</listitem>
</varlistentry>
<varlistentry>
<term>result</term>
<listitem>
<para>Zero if the connection to the server is alive. Nonzero if an
error occurred. A nonzero return does not indicate whether
the MySQL server itself is down; the connection might be
broken for other reasons such as network problems. </para>
<para>Error list:</para>
<itemizedlist>
<listitem>
<para>CR_COMMANDS_OUT_OF_SYNC Commands were executed in
an improper order.</para>
</listitem>
<listitem>
<para>CR_SERVER_GONE_ERROR The MySQL server has gone
away.</para>
</listitem>
<listitem>
<para>CR_UNKNOWN_ERROR An unknown error occurred.</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
username = 'glpk'; // Put your username
password = 'gnu'; // Put your password
database = 'glpk';
port = 3306; // use netstat -a | grep mysql to locate the mysql port
// or ps -elf | grep mysql and locate --port
myhost = 'localhost'; // localhost most of the time
sql_ptr = mysql_init();
status = mysql_real_connect(sql_ptr, myhost, username, password, database, port);
res = mysql_ping(sql_ptr);
mysql_close(sql_ptr);
]]></programlisting>
</refsection>
<refsection>
<title>See Also</title>
<simplelist type="inline">
<member><link linkend="mysql_init">mysql_init</link></member>
<member><link linkend="mysql_real_connect">mysql_real_connect</link></member>
<member><link linkend="mysql_close">mysql_close</link></member>
</simplelist>
</refsection>
<refsection>
<title>Authors</title>
<simplelist type="vert">
<member>Yann COLLETTE</member>
</simplelist>
</refsection>
</refentry>
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