T-SQL problems have a way of tricking programmers. At first glance, those problems look so simple that you're certain you'll need only a few minutes to solve them. However, after you start working on a solution, you realize that the problem isn't so simple after all. Validating IP addresses can be one of those problems. In particular, you might be stymied when you try to write a CHECK constraint that validates character strings containing IP addresses entered into a table column. I found this ch...