Exercise #30 (tips and solutions)
Exercise #30 (tips and solutions)
To overcome the problem of getting double, triple, etc. sums, you just need to perform the appropriate group operation for each table individually BEFORE combining them. This reduces this task to exercise 29, which seemingly didn’t cause any difficulties and thus isn’t analyzed in this tutorial.
This isn’t the only possible way to solve this task. Check out forum of the site to see other solutions.