Prepare all of the salad ingredients and add all of them except the corn to a large bowl and mix well. Then add the corn to the top and set aside. (If you add the corn in the beginning it can darken in color from all the other beans. It will still taste fine, I just think it looks prettier to add it at the end.)
In a small saucepan bring the vinegar, sugar and oil to a boil and stir together until combined and sugar is completely dissolved.
Pour overtop of the bean mixture and gently mix.
Cover and chill overnight to allow for the flavors to develop.