Handling changing requirements gracefully

[wayne jr]

Suppose you have a database that is processing forms which have legally madated fields but later, a change in the law/legal requirement mandates a change database. This could implay different things suchs as breaking one field into multiple fields, or combining multiple fields into one field or the addition/deletion of fields.

Now, since the old records have to stay the same in case an amended report is made. What is the usual way to address this type of issue? The code base for server (php) and the client (jQuery) have to deal with this as well. The client side could just load the appropriate js file I suppose.

Any suggestions?