This video shows how to create an index column for each category in your table. Within each category the number then starts from 1 and increases sequentially up to the number of items in your category.
00:00 Introduction
00:26 Add Regular Index
01:02 Method 1: Separate Column
03:15 Method 2: Adjust Group By - Lose Data Type
07:28 Method 3: Adjust Group By - Define Data Type