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Showing posts from June, 2016

Back To Basics - Validating a date

Recently, a lot of my time has been spent working on systems written by someone else. One of the biggest problems I see in these systems is a lack of basic validation. Limiting the length of strings, requiring values and making sure values fall into the allowed range.

The one that annoys me the most is date validation. Let's be clear, I'm talking about some basic rules to make insure that a date is not just a valid date but is a reasonable value for the data element. January 1, 1900 is a valid date except if we're talking about a birth date for living people. The current oldest living person is 116 years old and there aren't that many people over 100. Ask yourself this question, "Are they going to be in my system?" Probably not, so don't allow it.

This simple rule will keep a lot date typos out of your system. Remember, dates come in different formats MM/dd/yyyy or dd/MM/yyyy or yyyy/MM/dd. Some users will enter zeros such as 08/02/1991 while others might…