Convincing a client to adhere to web standards

This depends on what the client requires this data for. Lets just say the client needs to send information to people who were born between 1970 and 1980 he would be able to target anyone within that date range, but not to a specific year, month, day.

It's always difficult when a client is wanting something that sounds impractical. The best thing to to is isolate, tackle and overcome.

Isolate: why does the client need theese specific date ranges, what purpose does it ultimately serve?

Tackle: tackle the task in a professional manor. If it turns out the client will have issues, or it wouldn't be beneficial to use a method, then suggest an alternative.

Overcome: overcome the task and implement what the client decides on.

Honestly a client hardly ever hires a professional that hasn't made some compromise with them. It's a rare case when it happens, just express you professional opinion and try to understand things from a clients need perspective. This will help you both understand eachother.

@Joseph, it's a "New Member Form" for people to fill out on a tablet at real estate events. It's going into SugarCRM.

Those are good bullet points though, I will be keeping those in my toolkit for future use. Thanks a lot

Your welcome Eric, I'm happy if I helped in any way. :)

The use of age ranges is a common practice in surveys. In fact in a lot of ways it makes better sense to do that then ask for a particular birth date.

The problem comes in, in storing data that is more specific then you actually collected. The correct way to store that data is to store them as actual values based on a lookup table.

In your case the answer is 5, the 6th element of the list starting from 0.