public TableExpression getTargetTable() {
   TableExpression tableExpr = null;
   QueryValueExpression expr = sqlPredicate.getRightValueExpr();
   if (expr instanceof ValueExpressionColumn) {
     tableExpr =
         ExpressionHelper.getTableExprForValueExpressionColumn((ValueExpressionColumn) expr);
   }
   return tableExpr;
 }
 protected LabelValuePair createComboBoxItem(String newValue) {
   return new LabelValuePair(newValue, ExpressionHelper.createExpression(newValue));
 }