How Null values are programmatically implemented in mysql database?

Question

How the database solved the problem of NULL values in mysql db? E.g In C, null is implemented as #define NULL '\0'

It’s a flag. Why do you ask? – Sami Kuhmonen Feb 25 '18 at 17:06 — Sami Kuhmonen, Feb 25 '18 at 17:06

score 1 · Answer 1 · answered Feb 25 '18 at 17:10

In general, databases implement NULL values by having a separate flag column for each nullable column.

The flag is "hidden" in the sense that it is not accessed directly. Instead, the engine understands how and when to reference the flag.

NULL is -- in general -- not implemented as a "special" value.

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