[Code Philosophy Essay] null is not 'nothing' but 'not yet decided' — I left the empty values unfilled

There is a field left emptyOctober 14, 2026. Wednesday. A field on the screen remains empty. In the code, that emptiness is ...

How to handle NULL (empty fields) and common pitfalls

For those new to data analysis, I will explain how to handle NULL (empty fields), where mistakes are most common in SQL, ...