refactor: Refactor the code and remove the examples (#12)

* reactor: reactor NewQuery

* reactor: delete gen

* refactor: refactor select column

* refactor: refactor set column

* refactor: use getColumnName

* refactor: delete +gplus

* refactor: refactor updateById

* refactor: update getPKColumnName to getPkColumnName

* refactor: delete example

Author: afumu