 comparison operators order first by the range lower
   bounds, and only if those are equal do they compare the upper bounds.  The
   multirange operators compare each range until one is unequal. This
   does not usually result in a useful overall ordering, but the operators are
   provided to allow unique indexes to be constructed on ranges.
  </p><div class="table" id="RANGE-OPERATORS-TABLE"><p class="title"><strong>Table 9.55. Range Operators</strong></p><div class="table-contents"><table class="table"