to use MSSQL-connections on Linux with PHP7 you can use PDO with PDO_DBLIB.
Install driver using this command:
sudo apt-get install php7.0-sybase
then simply connect with this:
<?php
$dsn = "dblib:host=" . $host . ":1433;dbname=" . $database;
$dblink = new PDO ($dsn, $user, $pass);
?>
I got problems when i used the hostname, so i switched to the IP of the server.
Later I got problems to insert records into MSSQL-table.
This settings helped me out:
<?php
$dblink->exec("SET ANSI_WARNINGS ON");
$dblink->exec("SET ANSI_PADDING ON");
$dblink->exec("SET ANSI_NULLS ON");
$dblink->exec("SET QUOTED_IDENTIFIER ON");
$dblink->exec("SET CONCAT_NULL_YIELDS_NULL ON");
?>