If Product 1 is in the database currently, listed with collections A, B, C and D and I want it updated to be collection A, D, and E-- will updating my import list as A;D;E remove collection B and C and newly create E? Or will it just add E to the collections that already existed in the database (A;B;C;D)?
Hi 
When using wixData.update() , the update will replace all the data in the entry which matches the provided ID.