>>>Is there any other way to change the structure of the existing table?
>
>We used to change structure programmatically by creating a temp table with the new structure, appending the old data into it, renaming the existing table as .bak, then renaming the temp table as the original table. But it doesn't work so well if your table is in a dbc.

This can be improved if you create a temp dbc, then copy to a new table in that dbc (there's a syntax for that in the copy command); at least you can get the long field names and indexes. Other extended dbc-bound properties are a tad tougher.

But if you create a whole new directory with the new tables, database etc, and then append only where structure is different (i.e. the whole arrays you get with ataginfo() and afields() are not identical), otherwise just copy files as they are, then rename directories - that works, and isn't too slow either. The plain file copy is fast even on big tables, and the tables where you still have changes probably didn't have the time to grow too much... but then even if they did, you'd have to spend pretty much the same time.

Either way, you need to be alone with the tables for the duration of this, or else you may get a dirty copy - parent-child relations may be out of sync, various orphans or mismatches may happen. Using Alter Table may look better, if you want to manage it manually... and have to do it fast.