code: protected void processPlainSelect(PlainSelect plainSelect, int level) {
          if (level > 1) {
              if (isNotEmptyList(plainSelect.getOrderByElements())) {
                  if (plainSelect.getTop() == null) {
                      plainSelect.setTop(TOP100_PERCENT);
                  }
              }
          }
          if (plainSelect.getFromItem() != null) {
              processFromItem(plainSelect.getFromItem(), level + 1);
          }
          if (plainSelect.getJoins() != null && plainSelect.getJoins().size() > 0) {
              List<Join> joins = plainSelect.getJoins();
              for (Join join : joins) {
                  if (join.getRightItem() != null) {
                      processFromItem(join.getRightItem(), level + 1);
                  }
              }
          }
      }
docs: 处理PlainSelect类型的selectBody
  
  @param plainSelect