Database query

<?php
//连接数据库的参数
$host = "localhost";
$user = "root";
$pass = "zq19890319";
$db = "phpdev";
//创建一个mysql连接
$connection = mysql_connect($host, $user, $pass) or die("Unable to connect!");
//选择一个数据库
mysql_select_db($db) or die("Unable to select database!");
//开始查询
$query = "SELECT * FROM symbols";
//执行SQL语句
$result = mysql_query($query) or die("Error in query: $query. ".mysql_error());
//显示返回的记录集行数
if(mysql_num_rows($result)>0){
//如果返回的数据集行数大于0，则开始以表格的形式显示
echo "<table cellpadding=10 border=1>";
while($row=mysql_fetch_row($result)){
echo "<tr>";
echo "<td>".$row[0]."</td>";
echo "<td>".$row[1]."</td>";
echo "<td>".$row[2]."</td>";
echo "</tr>";
}
echo "</table>";
}
else{
echo "记录未找到！";
}
//释放记录集所占用的内存
mysql_free_result($result);
//关闭该数据库连接
mysql_close($connection);
?>