If you're already using forms to capture information you could customize online form web part to make it capture record id from query string for example and pass it to cms:BizForm ItemID field - so bizform will load the record.
Is is possible to achieve desired behavior with page types and user contribution.
There is web part in Kentico marketplace that will do what you need for the custom table.
Also you could implement front end with javascript and use Kentico REST service for getting/inserting/updating data.
Hope that helps.