The main risk with Joins is data duplication. Rather than a theoretical explanation, consider the following example.
If you want to reproduce the example, you can download the file Data duplication example file from my website, book.ladataviz.com in, the Chapter 4: Connect To Data and Simple Transformation section, or use this direct link: https://ladataviz.com/wp-content/uploads/2018/09/Data-duplication-example.xlsx.
The Data duplication example Excel file contains two sheets: Sales and Product. Sales contains the following data:
The total volume of sales is 300.
Product contains the following data:
Now let's join the two tables and ...
