PHP与MS sql server

Question

I'm trying to get the user's hashed password from my database but this function doesn't seem to return if it's valid or not, I feel like there's something wrong with assigning $hashedPass to the sqlsrv_prepare function. What's the proper way to do it if I'm doing it wrong?

function validate($conn, $username, $password)

{ 
    $isValid = false;

    $sql = "SELECT UserPassword 
            FROM dbo.Users(FullName,Username,UserPassword,Email,PhoneNumber) 
            WHERE Username = ?";
    $hashedPass = sqlsrv_prepare($conn, $sql, array(&$username));

    sqlsrv_execute($hashedPass);
    sqlsrv_fetch($hashedPass);
    sqlsrv_free_stmt($hashedPass);


    if(crypt($password, $hashedPass) == $hashedPass)
        $isValid = true;

    return $isValid;
}