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
Post Mortem
![https://bram-adams.ghost.io/content/images/2023/01/Complex-SQL-Query-Breakdown-Step-By-Step-Screenshot-2023-01-09-17-42-25.png](https://www.bramadams.dev/content/images/2023/01/Complex-SQL-Query-Breakdown-Step-By-Step-Screenshot-2023-01-09-17-42-25.png)
![https://bram-adams.ghost.io/content/images/2023/01/Complex-SQL-Query-Breakdown-Step-By-Step-Screenshot-2023-01-09-17-46-07.png](https://www.bramadams.dev/content/images/2023/01/Complex-SQL-Query-Breakdown-Step-By-Step-Screenshot-2023-01-09-17-46-07.png)
![https://bram-adams.ghost.io/content/images/2023/01/LEFT-JOIN-Screenshot-2023-01-09-17-48-36.png](https://www.bramadams.dev/content/images/2023/01/LEFT-JOIN-Screenshot-2023-01-09-17-48-36.png)