请高手解释一下非常简单的PHP代码。

<?php$db = mysql_connect("localhost", "root", "");mysql_select_db("aaa",$db);$result = mysql_query("SELECT * FROM a",$db);if ($result === false) die("failed");while ($fields = mysql_fetch_row($result)) {for ($i=0, $max=sizeof($fields); $i < $max; $i++) {print $fields[$i].' ';}print "<br>";}?>

$db = mysql_connect("localhost", "root", "");

mysql_select_db("aaa",$db);

连接数据库

$result = mysql_query("SELECT * FROM a",$db);

if ($result === false) die("failed");

执行查询语句SELECT * FROM a

while ($fields = mysql_fetch_row($result)) {

for ($i=0, $max=sizeof($fields); $i < $max; $i++) {

print $fields[$i].' ';

}

print "<br>";

}

显示查询返回的结果