How to union between two datasets with a variable number of fields, using SQL?

I have two query results from different tables like below.

ID　　F1　　F2　　F3　　　　　　ID　　F3　　F4　　F5

S1　 d11　　d12 　d13 　　　　　S2　　d23 　d24　 d25

S2　 d21　　d22 　d23 　　　　　S3　　d33 　d34开发者_Go百科　 d35

S3　 d31　　d32 　d33 　　　　　S4　　d43 　d44　 d45

ID and F# are field names, the others are values. I want to get a new result in a similar form to the following from the results above.

ID　　F1　　F2　　F3　　F4　　F5

S1　 d11　　d12 　d13

S2　 d21　　d22 　d23

S2　　　　　　　　d23　 d24　　d25

S3　 d31　　d32 　d33

S3　　　　　　　　d33　 d34　　d35

S4　　　　　　　　d43　 d44　　d45

Is this possible in SQL? I'm programming in VBA with ADO. I've never done such a task before.

Note that the fields of the first two tables are dynamic. I can't predict how many there are or what they are.

select ID, F1, F2, F3, NULL as F4, NULL as F5
from Table1
union all
select ID, NULL as F1, NULL as F2, F3, F4, F5
from Table2

Maybe you could do a full outer join on two sub-queries that generate a fake join key that is never equal. This way you could use a select * to get any columns that exist in the two tables.

select * from 
(select 1 as MY_ID, Table1.* from Table1) AS A
FULL OUTER JOIN
(select 2 as MY_ID, Table2.* from Table2) AS B
ON A.MY_ID = B.MY_ID