public function SelectCase($Field, $Options, $Alias) {
      $CaseOptions = '';
      foreach ($Options as $Key => $Val) {
         if ($Key == '')
            $CaseOptions .= ' else ' . $Val;
         else
            $CaseOptions .= ' when ' . $Key . ' then ' . $Val;
      }
      
      $Expr = array('Field' => $Field, 'Function' => '', 'Alias' => $Alias, 'CaseOptions' => $CaseOptions);
      
      if($Alias == '')
         $this->_Selects[] = $Expr;
      else
         $this->_Selects[$Alias] = $Expr;
         
      return $this;
   }