Hi @Sophia_Koch,
It is to my knowledge that you cannot join datasets if they are from different data prep experiences. I would recommend creating a brand-new dataset from scratch.
- Go to Datasets and click New Dataset
- Start with your sales data as the base table
- Left join your product info table to it (one row per product, so no duplication)
- Left join your additional data table separately if needed
Additionally, depending on your scenario you could select “Use custom SQL” during the dataset configuration screen. Write a standard query that establishes Dataset 3 as your primary FROM clause, then left join the other tables to it. I believe this community post might be helpful for this case: Can I join multiple tables in Quicksight?
Feel free to reply with any updates!