Extending Existing Db Table By A Module


i’m currently researching best way for a module to extend (existing) database table(s):

So fare I have come up with two strategies:

1.) write an install routine/function in the module that checks upon installation of the module if the needed database changes already are made, and if not so, execute them

2.) use the yii migrate tool

Any other ideas/thoughts? What would you do?

Thanks in advance!