I have a text file caled db_def.sql. Right now (during initial development
of a site) it looks kinda like this:

DROP TABLES AND SEQUENCES etc...
ADD SEQUENCES
ADD TABLES
INSERT CERTAIN RECORDS...

Now that I'm getting farther and farther into development, I want a text
file that does this:

BACKUP ALL EXISTING RECORDS
DELETE TABLES
ADD TABLES
PUT BACK BACKEDUP RECORDS

How do I do this?
What do I need to be carefull of?
How should i handle SEQUENCES?


Thanks
Alex