MySQL is pretty much the only db resource that for whatever reason they decided to force a global scope out of. Because of this, the signature usually accepts a connection resource as the last argument and is optional. Every other db library typically requires the use of the connection in scope, and requires it as the first argument (if its procedural). Another reason that PDO is a better alternative.
I don't typically use PDO as I have a custom abstraction layer that isn't limited to just sql. Documentation is fairly straight forward though.
$sDSN = 'sqlsrv:Server=localhost;Database=urdb';
$sUser = 'UrUser';
$sPass = 'UrPass';
$pdo = new PDO($sDSN, $sUser, $sPass);
$stmt = $pdo->prepare('UPDATE records SET StreetPrefix=?, ...');
Dormlich can give much better examples of PDO usage and error handling.
Also, all of this logic needs to move to the else:
$_StreetID = (int)($_GET['StreetID']);
$_sql ="SELECT * FROM records WHERE StreetID=$_StreetID";
$_rs = sqlsrv_query($_sql);