mysql connect返回null 原因是用了
mysqli_error($con)
调试语句
实际应该使用mysqli_connect_error()
$con = mysqli_connect($host, $username, $password, $dbname, $dbprot);
var_dump("host:".$host, "username:".$username, "password:".$password, "dbname:".$dbname, "dbprot:".$dbprot);
if (!$con) {
var_dump("连接错误: " . mysqli_connect_error());
die("连接错误: " . mysqli_connect_error());
}