visual problem

Hello,
I created a table with 2 date fields (start date and end date) and I would like to see these two fields replaced a visual point of view by one to select a month but it is not in the database data. How to do that?

I created a new menu to insert some statistics. For the moment these statistics are monthly, but later they will be quarterly, annual or dates to dates. This is why I immediately creates a table with 2 date fields (start date and end date) and fields useful for managing my statistics. Following tools facilitating the design that you have already developed, I created an object in the model folder with the same fields in the database données.Il behaves like the object "project" and so when I click about where to create a new item, I end up with all the fields specified in the object and in this base.
This is where my problem comes because today I find myself with the start date and end date on the present me to create this new object, and I will wish for the moment he could not see these two date fields but rather a field just to choose a number between 1 and 12 that corresponds to a month and I would do the background processing to select the date at the beginning and end of the month. How to do that?