php连接数据库代码应用分析

<?php
$db_host="hostnameisdatabaseserver";
$db_database="databasename";
$db_username="username";
$db_password="password";
$connection=mysql_connect($db_host,$db_username,$db_password);//连接到数据库
mysql_query("setnames"utf8"");//编码转化
if(!$connection){
die("couldnotconnecttothedatabase:</br>".mysql_error());//诊断连接错误
}
$db_selecct=mysql_select_db($db_database);//选择数据库
if(!$db_selecct)
{
die("couldnottothedatabase</br>".mysql_error());
}
$query="select*frommsu";//构建查询语句
$result=mysql_query($query);//执行查询
if(!$result)
{
die("couldnottothedatabase</br>".mysql_error());
}
//arraymysql_fetch_row(resource$result);
while($result_row=mysql_fetch_row(($result)))//取出结果并显示
{
$num=$result_row[0];
$age=$result_row[1];
$name=$result_row[2];
echo"<tr>";
echo"<td>$num</td>";
echo"<td>$age</td>";
echo"<td>$name</td>";
echo"</tr>";
}
mysql_close($connection);//关闭连接
?>