When should one try to eliminate a switch statement? [duplicate]

Answer 1

I wouldn't use an if. An if would be less clear than the switch. The switch is telling me that you are comparing the same thing throughout.

Just to scare people, this is less clear than your code:

if (string) reader[discountTypeIndex]) == "A")
   p.DiscountType = DiscountType.Discountable;
else if (string) reader[discountTypeIndex]) == "B")
   p.DiscountType = DiscountType.Loss;
else if (string) reader[discountTypeIndex]) == "O")
   p.DiscountType = DiscountType.Other;

This switch may be OK, you might want to look at @Talljoe suggestion.