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<?xml version="1.0" encoding="UTF-8"?>
<refentry version="5.0-subset Scilab" xml:id="mysql_field_count" 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_field_count</refname>
<refpurpose>Returns the number of columns for the most recent query on the connection.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>fieldnr = mysql_field_count(mysql)</synopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>Returns the number of columns for the most recent query on the connection.</para>
<para>The normal use of this function is when <literal>mysql_store_result</literal>
returned NULL (and thus you have no result set pointer).</para>
<para>In this case, you can call <literal>mysql_field_count</literal>
to determine whether <literal>mysql_store_result</literal>
should have produced a nonempty result.</para>
<para>This allows the client program to take proper action without
knowing whether the query was a <literal>SELECT</literal>
(or <literal>SELECT</literal>-like) statement.</para>
<para>An alternative is to replace the <literal>mysql_field_count(mysql)</literal> call
with <literal>mysql_errno(mysql)</literal>.</para>
<para>In this case, you are checking directly for an error from
<literal>mysql_store_result</literal> rather than inferring
from the value of <literal>mysql_field_count</literal> whether
the statement was a <literal>SELECT</literal>.</para>
</refsection>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term>mysql</term>
<listitem>
<para>a MySQL pointer</para>
</listitem>
</varlistentry>
<varlistentry>
<term>fieldnr</term>
<listitem>
<para>An unsigned integer representing the number of columns in a result set.</para>
</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);
sql = sprintf("select val from sudoku where val>=0 and val<7;\n");
status = mysql_real_query(sql_ptr, sql);
rs = mysql_store_result(sql_ptr);
res = mysql_field_count(sql_ptr);
disp(res);
mysql_free_result(rs);
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_query">mysql_real_query</link></member>
<member><link linkend="mysql_real_connect">mysql_real_connect</link></member>
<member><link linkend="mysql_close">mysql_close</link></member>
<member><link linkend="mysql_free_result">mysql_free_result</link></member>
<member><link linkend="mysql_store_result">mysql_store_result</link></member>
</simplelist>
</refsection>
<refsection>
<title>Authors</title>
<simplelist type="vert">
<member>Yann COLLETTE</member>
</simplelist>
</refsection>
</refentry>
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