我在安装lamp的时候，apache2.4，MySql57,PHP7.0都是下了压缩包到机子上源码安装的，apache和php能用，浏览器上可显示。但是运行如下例子的时候无反应

test test fucking test

$mysqli = new mysqli("localhost", "root", "password", "dbname");

if ($mysqli->connect_errno) {

echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;

}

echo $mysqli->host_info . "\n";

$mysqli = new mysqli("127.0.0.1", "root", "password", "dbname", 3306);

if ($mysqli->connect_errno) {

echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;

}

echo $mysqli->host_info . "\n";

?>

我觉得是连接不上mysql的原因，且可能因为没有mysqli 扩展库，然后查阅各种方法例如如下安装

apt-get install php7.0-mysqli php7.0-mysqlnd

但是没有任何作用。

望各位大神指点迷津，我该怎么安装mysqli。谢谢！