Complex SQL Query Breakdown Step By Step
<https://www.youtube.com/watch?v=f1vuGPuug9s&ab_channel=DatabaseStar>
03:02
use the FROM clause to understand tables in the query
04:60
LEFT JOIN (only join items into the union from the left table) uses a subquery where we can SELECT inside and the JOIN it on a field to the computed table
08:50
any filters? HAVING is filtering where sum values != 0
14:34
Run the main query in parts