ramlisting">
CHECK ( x = 1 )
CHECK ( county IN ( 'Oxfordshire', 'Buckinghamshire', 'Warwickshire' ))
CHECK ( outletID &gt;= 100 AND outletID &lt; 200 )
</pre><p>
         Ensure that the constraints guarantee that there is no overlap
         between the key values permitted in different child tables.  A common
         mistake is to set up range constraints like:
</p><pre class="programlisting">
CHECK ( outletID BETWEEN 100 AND 200 )
CHECK ( outletID BETWEEN 200 AND 300 )
</pre><p>
         This is wrong s