php-doc-en/reference/mysql/functions/mysql-query.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.11 $ -->
<!-- splitted from ./en/functions/mysql.xml, last change in rev 1.62 -->
  <refentry id="function.mysql-query">
   <refnamediv>
    <refname>mysql_query</refname>
    <refpurpose>Send a MySQL query</refpurpose>
   </refnamediv>

   <refsect1 role="description">
    &reftitle.description;
    <methodsynopsis>
     <type>resource</type><methodname>mysql_query</methodname>
     <methodparam><type>string</type><parameter>query</parameter></methodparam>
     <methodparam choice="opt"><type>resource</type><parameter>link_identifier</parameter></methodparam>
    </methodsynopsis>
    <para>
     <function>mysql_query</function> sends a query (to the currently
     active database on the server that's associated with the
     specified <parameter>link_identifier</parameter>).
    </para>
   </refsect1>

   <refsect1 role="parameters">
    &reftitle.parameters;
    <para>
     <variablelist>
      <varlistentry>
       <term><parameter>query</parameter></term>
       <listitem>
        <para>
         A SQL query
        </para>
        <para>
         The query string should not end with a semicolon.
        </para>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term><parameter>link_identifier</parameter></term>
       <listitem>
        <para>
         A link identifier, as returned by <function>mysql_connect</function>.
        </para>
        <para>
         If <parameter>link_identifier</parameter> isn't specified, the last
         opened link is assumed.  If no link is open, the function tries
         to establish a link as if <function>mysql_connect</function> was
         called with no arguments, and use it. The result of the query is buffered.
        </para>
       </listitem>
      </varlistentry>
     </variablelist>
    </para>
   </refsect1>

   <refsect1 role="returnvalues">
    &reftitle.returnvalues;
    <para>
     For SELECT, SHOW, DESCRIBE or EXPLAIN statements,
     <function>mysql_query</function> 
     returns a <type>resource</type> on success, and &false; on
     error.
    </para>
    <para>
     For other type of SQL statements, UPDATE, DELETE, DROP, etc,
     <function>mysql_query</function> returns &true; on success
     and &false; on error.
    </para>
    <para>
     The returned result resource should be passed to
     <function>mysql_fetch_array</function>, and other
     functions for dealing with result tables, to access the returned data.
    </para>
    <para>
     Use <function>mysql_num_rows</function> to find out how many rows
     were returned for a SELECT statement or
     <function>mysql_affected_rows</function> to find out how many
     rows were affected by a DELETE, INSERT, REPLACE, or UPDATE
     statement.
    </para>
    <para>
     <function>mysql_query</function> will also fail and return &false;
     if the user does not have permission to access the table(s) referenced by
     the query.
    </para>
   </refsect1>

   <refsect1 role="examples">
    &reftitle.examples;
    <para>
     <example>
      <title>Invalid Query</title>
      <para>
       The following query is syntactically invalid, so
       <function>mysql_query</function> fails and returns &false;.
      </para>
      <programlisting role="php">
<![CDATA[
<?php
$result = mysql_query('SELECT * WHERE 1=1');
if (!$result) {
    die('Invalid query: ' . mysql_error());
}

?>
]]>
      </programlisting>
     </example>
    </para>
    <para>
     <example>
      <title>Valid Query</title>
      <para>
       The following query is valid, so <function>mysql_query</function>
       returns a <type>resource</type>.
      </para>
      <programlisting role="php">
<![CDATA[
<?php
// This could be supplied by a user, for example
$firstname = 'fred';
$lastname  = 'fox';

// Formulate Query
// This is the best way to perform a SQL query
// For more examples, see mysql_real_escape_string()
$query = sprintf("SELECT firstname, lastname, address, age FROM friends WHERE firstname='%s' AND lastname='%s'",
    mysql_real_escape_string($firstname),
    mysql_real_escape_string($lastname));

// Perform Query
$result = mysql_query($query);

// Check result
// This shows the actual query sent to MySQL, and the error. Useful for debugging.
if (!$result) {
    $message  = 'Invalid query: ' . mysql_error() . "\n";
    $message .= 'Whole query: ' . $query;
    die($message);
}

// Use result
// Attempting to print $result won't allow access to information in the resource
// One of the mysql result functions must be used
// See also mysql_result(), mysql_fetch_array(), mysql_fetch_row(), etc.
while ($row = mysql_fetch_assoc($result)) {
    echo $row['firstname'];
    echo $row['lastname'];
    echo $row['address'];
    echo $row['age'];
}

// Free the resources associated with the result set
// This is done automatically at the end of the script
mysql_free_result($result);
?>
]]>
      </programlisting>
     </example>
    </para>
   </refsect1>

   <refsect1 role="seealso">
    &reftitle.seealso;
    <para>
     See also 
     <function>mysql_unbuffered_query</function>,
     <function>mysql_fetch_assoc</function>,
     <function>mysql_error</function>,
     <function>mysql_result</function> and
     <function>mysql_connect</function>.
    </para>
   </refsect1>
  </refentry>

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