What do steps 3 and 5 mean?
How do you convert the existing data to the new format?
When I need to do a big change that includes modifying some columns of a table:
- I create a new table with the new structure
- I create a script that copies and converts the data from the old format on the old table to the new format on the new table
- I work on the app and test it. While I test it I keep running the conversion script until the development app works with the new tables. When it works…
- (In the night when no one is using the app) I run the conversion script for the last time
- I merge to the production branch
- I delete the old table
How do you do something similar while working with two databases?
Is it possible for an app to copy and convert from a table in a database to a table in another database?