-To add some product and create a tree of categories you can use the following syntax in CSV file:
item_id,item_name,category
123,Product1,Category Name>Sub Category 1>Sub Sub Category 1
345,Product2,Category Name>Sub Category 1>Sub Sub Category 2
This will add or update 2 products and assign them to categories 'Sub Sub Category 1' and 'Sub Sub Category 2' accordingly.
-To assign a product to several categories you can use the following syntax:
item_id,item_name,category
123,Product1,Category1;Subcategory2;Subsubcategory3
This will add or update Product1 and assign it to 3 categories subsequently - 'Category1', 'Subcategory2' and 'Subsubcategory3'.