php连接数据库

header('Content-Type: text/html; charset=utf8');
/*$username=;//数据库用户名
$userpass=;//数据库密码
$dbhost=//主机名
$dbdatabase="meiyongde";//数据库名*/
//生成一个连接
$link=mysqli_connect("localhost","admin","luoyingwen"); /*or die("Unable to connect to the MySQL!")*/
if(!$link){
echo "failed...";
exit(-1);
}else{
echo "success...<br>";
}
//选择一个需要操作的数据库
mysqli_select_db($link,"meiyongde");
//执行MySQL语句
$result=mysqli_query($link,"SELECT username,password FROM user");
//提取数据
while($row=mysqli_fetch_row($result)){
printf ("%s : %s",$row[0],$row[1]);
echo "<br>";}
mysqli_free_result($result);//释放集合
mysqli_close($link);//关闭数据库