mysql-data-seek.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.mysql-data-seek" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysql_data_seek</refname>
  <refpurpose>移动内部结果的指针</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <warning>
   &mysql.alternative.note;
   <simplelist role="alternatives">
    <member><function>mysqli_data_seek</function></member>
    <member><constant>PDO::FETCH_ORI_ABS</constant></member>
   </simplelist>
  </warning>
 </refsynopsisdiv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>mysql_data_seek</methodname>
   <methodparam><type>resource</type><parameter>result</parameter></methodparam>
   <methodparam><type>int</type><parameter>row_number</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>mysql_data_seek</function> 将指定的结果标识所关联的
   MySQL 结果内部的行指针移动到指定的行号。接着调用
   <function>mysql_fetch_row</function> 将返回那一行。
  </para>
  <para>
   <parameter>row_number</parameter> 从 0 开始。<parameter>row_number</parameter>
   的取值范围应该从 0 到 mysql_num_rows - 1。但是如果结果集为空（<function>mysql_num_rows</function>
   == 0），要将指针移动到 0 会失败并发出 <constant>E_WARNING</constant>
   级的错误，<function>mysql_data_seek</function> 将返回 &false;。
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    &mysql.result.description;
    <varlistentry> 
     <term><parameter>row_number</parameter></term> 
     <listitem>
      <para>
       想要设定的新的结果集指针的行数。
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mysql_data_seek</function> 示例</title>
    <programlisting role="php">
<![CDATA[
<?php
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
$db_selected = mysql_select_db('sample_db');
if (!$db_selected) {
    die('Could not select database: ' . mysql_error());
}
$query = 'SELECT last_name, first_name FROM friends';
$result = mysql_query($query);
if (!$result) {
    die('Query failed: ' . mysql_error());
}
/* fetch rows in reverse order */
for ($i = mysql_num_rows($result) - 1; $i >= 0; $i--) {
    if (!mysql_data_seek($result, $i)) {
        echo "Cannot seek to row $i: " . mysql_error() . "\n";
        continue;
    }

    if (!($row = mysql_fetch_assoc($result))) {
        continue;
    }

    echo $row['last_name'] . ' ' . $row['first_name'] . "<br />\n";
}

mysql_free_result($result);
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    <function>mysql_data_seek</function> 只能和
    <function>mysql_query</function> 结合起来使用，而不能用于
    <function>mysql_unbuffered_query</function>。
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso"> 
  &reftitle.seealso; 
  <para>
   <simplelist>
    <member><function>mysql_query</function></member>
    <member><function>mysql_num_rows</function></member>
    <member><function>mysql_fetch_row</function></member>
    <member><function>mysql_fetch_assoc</function></member>
    <member><function>mysql_fetch_array</function></member>
    <member><function>mysql_fetch_object</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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