Siva,
If your database structure is changing this often, I'd be cautious about automating validation until the structure stabilizes.
Typically, early in a development process, the database structures will change frequently (sometimes daily with a large application undergoing rapid development with multiple development projects). During this period, it doesn't make sense to automate the areas changing frequently because you'll drive yourself insane trying to get all the rework completed.
Where data structures are stable, automation serves to verify that the changes haven't had a negative impact on existing structures. Similarly, as long as you've got a known set of stable data, automation acts as your regression validation regardless of the queries you're using. If the data that you're validating is changing frequently, you don't want to validate via automation until it stabilizes.
I'd say as a thumbnail measurement that if maintaining automation to handle changes takes more than an hour out of your day, it's probably something that's not stable enough for automation, and taking your focus away from the core of verifying that the application is doing the correct things (Caveat: if there's a lot of development happening around something that was previously stable, you could easily get spikes of large amounts of maintenance to update for that particular upgraded feature. This shouldn't affect more than that one feature).