You need a Many To Many relationship; one piece of art can have many exhibitions and one exibition can have many pieces of art.
This is solved with a third table ( Exhibition Rows ).
You haven't to use neither names of exibition nor names of pieces of art... you have to use IDs
This is exactly what I need. I understand the ID's completely. I also understand that I have to make a third join table.
However, I am still wondering how I am going to fill the fields of this third (join) table. In this table I will have the ID's of the pieces of art and exhibitions. Do I have to fill these manually (with risk of mistakes) or can I have this done automatically?
It works very well now. I took a little while before I understoord that the join table is filled via the portals (if this option is clicked). But now it all makes sense to me.
Thank you very much.