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1) if you re-writing your application, then please consider the below
a) put all the database retrival stuff into a WCF and let it give the results, instead of actual ADO.NET
b) Ensure that the access is done through stored procedures or functions but not by direct select statemets.
By doing so, you will website will have an API for further improvement.
And also I would suggest you to take a look at the entity framework, which has more capability than just ADO.NET.
Hope this helps.