Having analyzed your query, see what happens when you run it like this (sorry had to trim it down a bit for readability 🙂 )

SELECT D1.SID_0COMPANY AS SID_0COMPANY

FROM ...

put both your query in an inline view then order the view...

Select * from

(

SELECT a, b, c from TableA

UNION

SELECT a, b, c from Table B

) RESULTS

ORDER BY a...