AddOrderByParams|通过实体Entity、字段名和asc/desc添加排序

• 方法
• SQL语句
• 完整代码
• 完整SQL

• 
          /// <summary>
          /// 添加 order by - AddOrderByParams +
          /// </summary>
          /// <param name="entity">表</param>
          /// <param name="infoName">字段名</param>
          /// <param name="orderBy">asc/desc|如果为空则按asc排序，否则如果全小写不是asc/desc，抛出异常</param>
          public void AddOrderByParams(BaseEntity entity, string infoName, string orderBy)
          {
              if(entity==null)
              {
  
                  throw new Exception
                      (
                          "方法："
                          + MethodBase.GetCurrentMethod().ReflectedType.FullName
                          + " "
                          + MethodBase.GetCurrentMethod().ToString()
                          + " 发生异常："
                          + "传入参数："
                          + "BaseEntity entity"
                          + "为null。"
                      );
              }
  
              if (infoName == null || infoName.Length == 0)
              {
  
                  throw new Exception
                      (
                          "方法："
                          + MethodBase.GetCurrentMethod().ReflectedType.FullName
                          + " "
                          + MethodBase.GetCurrentMethod().ToString()
                          + " 发生异常："
                          + "传入的字符串参数："
                          + "string infoName"
                          + "为null或为空。"
                      );
              }
  
              EntityFieldInfo info = entity.GetExistEntityFieldInfo(infoName);
  
  
              OrderByItem item = new OrderByItem(info);
  
              item.IsOrderBy = true;
  
              m_ListIOrderByItem.Add(item);
  
  
  
              if (orderBy == null || orderBy.Length == 0)
              {
                  item.emOrderByValue
                      = Enums.OrderBy.EmOrderBy.ASC;
  
                  return;
              }
  
              orderBy = orderBy.Trim().ToLower();
  
              if (orderBy.Length == 0)
              {
                  item.emOrderByValue
                      = Enums.OrderBy.EmOrderBy.ASC;
  
                  return;
              }
  
              if (orderBy == "asc")
              {
                  item.emOrderByValue
                      = Enums.OrderBy.EmOrderBy.ASC;
  
                  return;
  
              }
  
              if (orderBy == "desc")
              {
                  item.emOrderByValue
                      = Enums.OrderBy.EmOrderBy.DESC;
  
                  return;
              }
  
  
              throw new Exception
                  (
                      "方法："
                      + MethodBase.GetCurrentMethod().ReflectedType.FullName
                      + " "
                      + MethodBase.GetCurrentMethod().ToString()
                      + " 发生异常："
                      + "传入参数："
                      + "orderBy[" + orderBy + "]位无效的排序值"
                  );
          }
  
  

• 
  tc.TheName asc
  
  
  

•  
  #region TheSQLGet
  
      /// <summary>
      /// 获得输出的SQL语句
      /// </summary>
      /// <param name="xdbHelper"></param>
      /// <returns></returns>
      protected override string TheSQLGet(DBHelper xdbHelper)
      {
          #region 逻辑代码 
  
          string theResult = null;
  
          // 标识是否创建或打开数据库链接 //
          bool bIsCreate = true;
  
          if (xdbHelper == null)
          {
              // 如果 xdbHelper 为null //
              // 则new一个数据库操作实体 //
              xdbHelper
                  =
                  SlowX.DAL.Helpers.DBHelper.CreateDBHelper();
          }
          else
          {
              // 如果 xdbHelper 不为null //
              // 判断 xdbHelper是否打开链接 //
              // 相当于是否执行 xdbHelper.OpenDBHelper(); //
              bIsCreate = xdbHelper.IsNotOpen();
          }
  
          try
          {
              if (bIsCreate)
              {
                  // 没有打开，则打开链接 //
                  xdbHelper.OpenDBHelper();
              }
  
              // 业务逻辑操作实体 //
              // insert/update/delete等操作 //
              SlowX.ExamLib.Business.UTB_EXAM_STUDENT
                 bll
                 =
                 SlowX.ExamLib.Business.UTB_EXAM_STUDENT.instance;
  
              // 组合SQL的逻辑实体 //
              SlowX.ExamLib.Entity.UTB_EXAM_STUDENT
                  entity
                  =
                  new SlowX.ExamLib.Entity.UTB_EXAM_STUDENT();
  
              // 组合SQL的逻辑实体 //
              SlowX.ExamLib.Entity.UTB_EXAM_CLASS
                  entity_Class
                  =
                  new SlowX.ExamLib.Entity.UTB_EXAM_CLASS();
  
              ISelectDriver iselect = entity;
              IFromTableDriver ifrom = entity;
              IWhereDriver iwhere = entity;
              IOrderByDriver iorder = entity;
  
              // 设置Class表字段的表名前缀 //
              entity_Class.selectPreName = "C__";
  
              // 将UTB_EXAM_CLASS加入查询, UTB_EXAM_CLASS tc //
              ifrom.AddIFromTableItemWithBaseEntity("tc", entity_Class);
  
              // UTB_EXAM_STUDENT ==> select 输出 //
              iselect.AddISelectItemWithBaseEntity(entity);
  
              // UTB_EXAM_CLASS ==> select 输出 TheName as C__TheName //
              iselect.AddISelectItemWithEntityFieldInfo(entity_Class._TheName);
  
              // t.ClassId == tc.ID //
              iwhere.WhereAddInfo(entity._ClassId, entity_Class._ID);
  
  
              // ===调用代码=== //  
              iorder.AddOrderByParams(entity_Class, "TheName", "asc");
  
              // 其他排序：TheName asc //
              iorder.AddOrderByEm(entity._TheName, SlowX.Core.Enums.OrderBy.EmOrderBy.ASC);
              // 其他排序：ID asc //
              iorder.AddOrderByEm(entity._ID, SlowX.Core.Enums.OrderBy.EmOrderBy.ASC);
  
              // 执行List操作 //
              // 这里做DEMO，仅打印输出的SQL语句 //
              // bll.List(entity, xdbHelper);
              theResult
                  =
                  bll.i_iBuildSQL.BuildSqlList(entity, xdbHelper);
  
  
              if (bIsCreate)
              {
                  // 关闭数据库链接 //
                  // 如果用了事务，提交数据库链接 //
                  xdbHelper.EndDBHelper();
              }
          }
          catch (Exception err)
          {
              if (bIsCreate)
              {
                  // 关闭数据库链接 //
                  // 如果用了事务，回滚数据库链接 //
                  xdbHelper.TranDBHelper();
              }
  
              throw err;
          }
          finally
          {
              if (bIsCreate)
              {
                  // 判断数据库操作是否正确关闭 //
                  // 如果没有正确关闭，则关闭并抛出异常提示代码缺陷 //
                  xdbHelper.FinallyDBHelper();
              }
          }
  
          return theResult;
  
          #endregion 逻辑代码 
      }
  
      #endregion TheSQLGet
  
  
  
  
  

•  
  
  select 
  t.ID, t.TheName, t.ClassId, 
  t.CreateTime, t.UpdateTime, 
  tc.TheName as C__TheName
  from UTB_EXAM_STUDENT t , 
  UTB_EXAM_CLASS tc
  where t.ClassId = tc.ID
  order by 
  tc.TheName asc, t.TheName asc, t.ID asc
  
  
  
  select 
  t.ID, t.TheName, t.ClassId, 
  t.CreateTime, t.UpdateTime, 
  tc.TheName as C__TheName
  from UTB_EXAM_STUDENT t , 
  UTB_EXAM_CLASS tc
  where t.ClassId = tc.ID
  order by 
  tc.TheName asc, t.TheName asc, t.ID asc