How Do You Run Code To Check While Mid Coding?

I’d like to write the code in bits but I can’t check in bits. How do I run code to check without completing entire code?
For example, this code won’t run without WHOLE CODE. THX

WITH
customer_country_purchases AS
(
SELECT
i.customer_id,
c.country,
SUM(i.total) total_purchases
FROM invoice i
INNER JOIN customer c ON i.customer_id = c.customer_id
GROUP BY 1, 2
),

What exactly do you wish to check in bits?

Because you can write the code in bits and check the bits. For example,

  • you could first have just the SELECT to check out the columns from invoice.
  • you can then JOIN the two tables together and SELECT columns from both.
  • then you can use SUM before using GROUP BY. And so on…

But, of course, those bits won’t represent the actual output because you will get the actual/intended outcome only when the entire logic of the code has been written out. It is about logically structuring/designing the solution, so you can split it out into individual steps. And those steps build on top of each other to get the desired outcome.