>You've never worked in a system where numeric entries are (sometimes) stored as character data? I wouldn't design such a system, in normal circumstances, but they do exist, and they do need conversion or fixing.

I've had a system where most of the date fields were accompanied by a character field containing the same date... because the nature of the matter was historic, and the dates were coming from fliers, posters, tickets and other printed material, which was, well, designed with interests of commerce first, good time next, ..., and historical accuracy last. So often there were dates like 07/xx/195x - which were as good as it got. Can't convert nor can fix, it's already the best that can be done. If a correction comes, it's individual data entry, not fixing in code.