Description:
------------
This is the same bug as reported in bug: 39213. An empty string is returned as NULL.

Reproduce code:
---------------
$conn = mssql_connect('host','user','password', true);


mssql_query("CREATE TABLE #tmp(c VARCHAR(10) NULL)", $conn) or
die("error querying");

mssql_query("INSERT INTO #tmp VALUES('')", $conn) or die("error
querying");

$res = mssql_query("SELECT * FROM #tmp", $conn) or die("query");
$row = mssql_fetch_assoc($res);

$s = is_null($row['c']) ? 'NULL' : $row['c'];
echo "got -$s-\n";

Expected result:
----------------
var_dump($s) should print string(0) ""

Actual result:
--------------
var_dump($s) print NULL