Embedded SQL and Externally Described Data Structure

I've started using SQL in RPG and I can use a data structure based on the
file so that I don't have to hard code every field name in the file:

For Example:

D ResvhistR       E DS               ExtName( RESVHIST)

then I can open a cursor on the file RESVHIST with a SELECT * FROM RESVHIST
WHERE... blah blah blah

When I do a FETCH next from -cursor- into :ResvhistR I get all my field
names automatically without having to list every field under the ResvhistR
data structure and without having to name every field in the select
statement.

Is there some way to do this from a multiple-file join SQL statement? Like 
SELECT *
FROM RESVHIST, SHWFIL, DETLHIST 
WHERE ...blah blah blah

I tried to set up another data structure overlaid by the 2 or 3 files I need
but the compiler says I can't have a data structure as a subfield of another
data structure.

If I set up a data structure with all the fields I want hard-coded then it
works fine.... but I have to list every field name in the SELECT statement
and then have them in the same order in my data structure. 

I just wondered if I could take advantage of the external definitions for
each file and not have to worry about defining every single field I need
with multiple files. 

Thanks
Jim Sneddon
AS400 RPG Programmer
Allstate Ticketing
jsneddon@allstateticketing.com
www.showtickets.com

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