tematic
process has been applied, you really don't need to check the rest
of the data set.
&gt; 
&gt; Note also that having the data entry clerk check this 
&gt; constraint is not a 
&gt; practical solution.  Typos happen, humans make errors.

MW: This is a different case. Adding checks on data entry is
quite common. But it is not considered part of the static database
design (that the data model supports). It might also be a check
you run on the whole database periodically.
&gt; 
&gt; Adam
&gt; 
&gt; 
&gt;