SQLite Forum

Removing not null constraint doesn't behave correctly
(I'm hoping not to seem a nag, here.)

That is, IMO, a perfectly adequate cure for Bug1. However, it does nothing for Bug2.  To state Bug2 more succinctly: There is a sequence of inputs which leaves the running SQLite data structures in an ill-defined state, such that the parser either behaves oddly or is fed input poorly related to design intent.

A hint of the ill-defined state is in my post #2, stating that simply retrying the failing column add statement "works". The same statement, submitted twice in a row, fails the first time and succeeds the second time, with v3.32.2.  I think you would agree that this is odd and may indicate a deeper problem.  If the parser sees the same bogus input both times, it should fail both times unless it has become non-deterministic. And if it is fed bogus input the first time but not the second, then I would want to know why that first input cannot be something that produces an address fault or other undesirable effects.

I suspect that recompiling sqlite_schema is a good idea whenever it is modified. It could be a build-time option to allow DML or DDL on it at all and do the recompilation as prudence demands.