And is even worse, this is stuff that I have seen in ERPs (I integrate with several). One of them, not even use "date"/"decimal" types and all is mostly string

And is even worse, this is stuff that I have seen in ERPs (I integrate with several). One of them, not even use "date"/"decimal" types and all is mostly strings, there is not views or anything else, and the tables AND fields are called "F0001..".