RE: Table Definitions DDS or SQL?

Field sequence does not matter to applications but it does matter to
users who do queries. Getting all the fields in a table that are related
together makes queries easier to do. An example: Being a college we
record SAT scores for students. SATs use to have just two scores Math
and Reading and existed for many years and are near the "front" of the
fields in the student master table. SAT when added another test which
was added to the end of the existing table with about 30 fields between
the original two and the new SAT score. It would be nice to have the
three SAT scores in the same location in the table. CHGPF will let me do
that, ALTER TABLE will not unless I want to do the old unload/reload
process of all the data and use CPYF *MAP to do the reload

Can ALTER TABLE be used to rearrange fields in the file 
like CHGPF
can? 

No, but remember that the order of fields in an SQL table aren't
supposed to matter.