Re: OO versus RDB
Date: 30 Jun 2006 00:09:13 -0700
H. S. Lahman wrote:
> Responding to Marshall...
> >>It breaks the query, but not the problem solution that needs the data.
> > This sounds sensible, but isn't. Any schema-change breakage
> > will affect both query and code. If a queried column is deleted,
> > the query will need changing, but also the code has to reconsider
> > what it will do in the absence of the column.
> I'm afraid that is not true. Consider
> [changing the name of an attribute]
Sure, if the change is trivial (in that it has no associated change in semantics) it might not be the case that anything besides the query needs to change. You don't even need a view, just change "SELECT salary, ..." to "SELECT base_salary as salary, ..."
What about adding a new attribute that the application code needs to use? What about deleting an attribute that has no obvious default? What about moving an attribute to a different table such that its cardinality relative to the query changes?
Marshall Received on Fri Jun 30 2006 - 09:09:13 CEST