Question: I apologise in advance if this might seem simple as my assignment needs to be passed in 2 hours time and I don't have enough time to do some further research as I have another pending assignment to be submitted tonight. I only know the basic MYSQL commands and not these types. And this is one of the final questions left unanswered and is making me go nuts even if i have already read the JOIN documentation . Please help.

Say I have 4 tables

```
 _______________     _______________      _______________    _______________
|   customers   |   |     orders    |    | ordered_items |  |   products    |
|_______________|   |_______________|    |_______________|  |_______________|
|(pk)customer_id|   | (pk)order_id  |    |   (pk)id      |  |(pk)product_id |
|  first_name   |   |(fk)customer_id|    | (fk)order_id  |  |     name      |
|  last_name    |   |     date      |    |(fk)product_id |  |  description  |
|   contact_no  |   |               |    |    quantity   |  |     price     |
|_______________|   |_______________|    |_______________|  |_______________|      

```

How would i be able to query all the products ordered by (eg: customer\_id = '5')

I only know basic SQL like straight forward queries on 1 table and joins from 2 different, but since its 4 different tables having different relations to one another, how would i be able to get all the products ordered by a particular customer id?

Because its like get all the products from ordered products where order\_id = (\* orders by customer\_id = 5).

But what can be an optimised and best practice way in doing this type of query

Answer: 
```
> boxplot(decrease ~ treatment, data = OrchardSprays,
+         log = "y", col = "bisque")

```
I had the same issue. I figured out it was because my dataset had some zero values, so I substituted them for NA and it worked out. It's because boxplot function can't handle plotting the 0 values in the log scale (converges to infinite).