Complicated query

Hi,

I have two tables Trade table and Cons table. Records are inserted in
both the tables independent of each other. There are fields like
Exc_Ref, Qty, Date in both the tables.

I need to write a query which should give me records :

1. Where there is missing Exc_Ref value in either of the table. i.e.
If Trade table has a Exc_Ref value but missing in Cons table then that
record should be displayed. Similarly if Cons has a Exc_Ref value
which is not found in Trade table then that too should be displayed.

2. In case where both the tables have matching Exc_Ref data then it
should display the record only when the remaining column does not
match like Qty or Date.

Please help me to resolve this complicated query.

Thanks
Nick