使用 mysqli_free_result 释放内存：
<?php
$dbhost = 'localhost:3306'; // mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
mysqli_query($conn , "set names utf8");
$sql = 'SELECT runoob_id, runoob_title,
runoob_author, submission_date
FROM runoob_tbl';
mysqli_select_db( $conn, 'RUNOOB' );
$retval = mysqli_query( $conn, $sql );
if(! $retval )
{
die('无法读取数据: ' . mysqli_error($conn));
}
echo '<h2>菜鸟教程 mysqli_fetch_array 测试<h2>';
echo '<table border="1"><tr><td>教程 ID</td><td>标题</td><td>作者</td><td>提交日期</td></tr>';
while($row = mysqli_fetch_array($retval, MYSQLI_NUM))
{
echo "<tr><td> {$row[0]}</td> ".
"<td>{$row[1]} </td> ".
"<td>{$row[2]} </td> ".
"<td>{$row[3]} </td> ".
"</tr>";
}
echo '</table>';
// 释放内存
mysqli_free_result($retval);
mysqli_close($conn);
?>
