Is there any RDBMS Schema design assistance tool, which can check/critique the data-base design, suggest amends to improve normalization, suggest constraints, discover potential conflicts etc. ?
Note the idea is not so much of a diagramming tool, although if it is integrated in a diagramming tool, it would be swell. Alternatively, it could be something that works with SQL schema.
Preference would be towards FOSS tools.
I doubt you can really develop a program that can do this ... it really depends on what you're building. Normalization does not determine "good" design.