RE: SQL multiple selects

Traditionally this is done using only 1 sql statement.  Again 
using between.
D @SQLByCat       C     'Select * from dmitmmst +
D                        Where (WHSLC between +
D                        ? and ?) and +
D                        (CATCD1 between ? and ?) +
D                        Order By SAQYR desc'
If you want only 1 value for CATCD1 then you use that for 
both parameters. 
 If you want all, then use *loval and *hival.

OK, I'm stumped.  Is there some way within SQL of saying *loval and *hival.

I've googled and used the infocenter and I can't find it.

I defined them in RPG like the following:

D HiCat           S                   Like(CATCD1)
D                                     Inz(*Hival)
D LoCat           S                   Like(CATCD1)
D                                     Inz(*Loval)

then changed them if necessary.  But I still want to know if there is a way
within SQL.

Thanks.