SQL — SELECT, JOIN, aggregation, subqueries

What you'll learn

1. 1

   Imagine you have a big box of Lego bricks sorted into two trays: one for 'colours' and one for 'shapes'.

2. 2

   What's the first step to find all red circles using the Lego trays?

3. 3

   Here's a simple database of customers and orders:

4. 4

   Let's find all orders made by Alice using SQL:

5. 5

   Try it yourself: combine the Customers and Orders tables to list all customer names with their order items.

6. 6

   Which SQL keyword do you use to combine two tables?

7. 7

   Now let's count how many orders each customer made using aggregation:

8. 8

   What does COUNT(*) do in a SQL query?