What books collect examplesexamples and counterexamplescounterexamples (or also "solved exercises", for some suitable definition of "exercise") in
- real analysis,
- complex analysis,
- functional analysis,
- ODEs,
- PDEs?
The only book of this kind that I know of is the famous
Counterexamples in Analysis by Bernard R. Gelbaum and John M. H. Olmsted.