Add "OFFSET 0 ROWS" queries without an existing ordering or limit clause

Without this patch, subqueries with orderings result in an exception:

    ProgrammingError: ('42000', '[42000] [Microsoft][ODBC Driver 13 for
        SQL Server][SQL Server]The ORDER BY clause is invalid in views,
        inline functions, derived tables, subqueries, and common table
        expressions, unless TOP, OFFSET or FOR XML is also specified.
        (1033) (SQLExecDirectW)')

Resolves issue #12.

Author: randlet

mssql/compiler.py

@@ -307,6 +307,12 @@ def as_sql(self, with_limits=True, with_col_aliases=False):
                     params.extend(o_params)
                 result.append('ORDER BY %s' % ', '.join(ordering))
 
+                # For subqueres with an ORDER BY clause, SQL Server also
+                # requires a TOP or OFFSET clause which is not generated for
+                # Django 2.x.  See https://github.com/microsoft/mssql-django/issues/12
+                if django.VERSION < (3, 0, 0) and not (do_offset or do_limit):
+                    result.append("OFFSET 0 ROWS")
+
             # SQL Server requires the backend-specific emulation (2008 or earlier)
             # or an offset clause (2012 or newer) for offsetting
             if do_offset: