General version if new field or new state is handled correctly

Principle: If a version needs to add new fields or new state, the program must consider compatibility with historical old data, that is, the premise of proper operation of the program can not rely on the complete maintenance of history
Practice of proper implementation:
1 If a version involves new fields or new states, program compatibility scenarios and historical data maintenance scripts must be given during the design phase.
2 The correct release order is: Execute the DDL script first (if new field), then publish the application (the program is compatible with historical data), and finally execute the DML script to maintain historical data.

Benefits of this approach:
1 if the script does not maintain the data fully, the compatible program will work without rolling back the program.
2 forced encoding supports DDL-first release.
3 The program will not reject the service if the publishing order is insane.

We need to do this:
1 The design phase must consider the compatibility plan
2 The DDL script executes first and the program must be able to execute correctly

General version if new field or new state is handled correctly