话说C#程序员人手一个ORM，确实没有必要再写ORM了，不过我的ORM并不是新的，是从DBHelper演化过来的，算是DBHelper魔改版，今天小编就来说说关于c语言编程第七周?下面更多详细答案一起来看看吧!

c语言编程第七周（程序员人手一个ORM）

c语言编程第七周

话说C#程序员人手一个ORM，确实没有必要再写ORM了，不过我的ORM并不是新的，是从DBHelper演化过来的，算是DBHelper魔改版。

目前流行的ORM有EF、Dapper、SQLSugar、FreeSql、Chloe等，有经验的程序员总是在这些ORM基础上或者在DBHelper基础上再封装一套，再加上自己写ORM的，可谓人手一套ORM。可能是因为在框架当中，编写ORM，入门相对简单吧，但是做好很难。

主要是自己用的，如果别人要用的话，建议从gitee或github上拉源码下来，源码在手好控制，源码相对简单，有经验的程序员不难看懂，可以自己调试修改扩展，Lambda表达式是新支持的，如果Lambda hold不住，就使用原生SQL。

跟主流ORM相比还是比较欠缺的，它只是一个DBHelper。

源码地址(VS2015、.NET Framework 4.5.2)：

https://gitee.com/s0611163/DBHelper

https://github.com/0611163/DBHelper

.NET Core 5 版本源码地址(VS2019、.NET 5)：

https://gitee.com/s0611163/DBHelperCore

性能测试

DBHelper SqlSugar EntityFramework 增删改查 性能对比测试

https://www.cnblogs.com/s0611163/p/15814051.html

为什么每个主流ORM都说性能比EF好，都说EF性能不好？而我的测试结果显示EF性能挺好的，为了防止有缓存，每项测试前，重启程序再测，性能还是一样的。批量添加和修改，别的ORM是快很多，但它使用了别的专门的方法。

该ORM介绍及使用示例如下：

DBHelper简介

一款轻量级ORM，查询使用原生SQL，查询结果映射到实体类，增删改支持实体类，支持Oracle、MSSQL、MySQL、SQLite等多种数据库，有配套Model生成器，方便自己扩展以支持更多数据库

特点
  1. 支持Oracle、MSSQL、MySQL、SQLite四种数据库
  2. 方便扩展以支持更多关系数据库
  3. 有配套的Model生成器
  4. insert、update、delete操作无需写SQL
  5. 查询使用原生SQL
  6. 查询结果通过映射转成实体类或实体类集合
  7. 支持参数化查询，通过SqlString类提供非常方便的参数化查询
  8. 支持连接多个数据源
  9. 单表查询、单表分页查询、简单的联表分页查询支持Lambda表达式
  10. 支持原生SQL和Lambda表达式混写
优点
  1. 代码实现比较简单，有经验的程序员容易掌控代码，自己修改和扩展
  2. 查询使用原生SQL
缺点
  1. 联表查询对Lambda表达式的支持比较弱
  2. 复杂查询不支持Lambda表达式
建议
  1. 单表查询可以使用Lambda表达式
  2. 联表查询以及复杂查询建议使用原生SQL或原生SQL和Lambda表达式混写
示例定义数据库对象

public class DBHelper { #region 变量 private static ISessionHelper _sessionHelper = new SessionHelper(ConfigurationManager.ConnectionStrings["DefaultConnection"].ToString(), DBType.MySQL); #endregion #region 获取 ISession /// <summary> /// 获取 ISession /// </summary> public static ISession GetSession() { return _sessionHelper.GetSession(); } #endregion #region 获取 ISession (异步) /// <summary> /// 获取 ISession (异步) /// </summary> public static async Task<ISession> GetSessionAsync() { return await _sessionHelper.GetSessionAsync(); } #endregion }

使用Model生成器生成实体类
  1. 实体类放在Models文件夹中
  2. 扩展实体类放在ExtModels文件夹中
  3. 实体类和扩展实体类使用partial修饰，实际上是一个类，放在不同的文件中
  4. 如果需要添加自定义属性，请修改ExtModels，不要修改Models
实体类示例

/// <summary> /// 订单表 /// </summary> [Serializable] [DBTable("bs_order")] public partial class BsOrder { /// <summary> /// 主键 /// </summary> [DBKey] [DBField] public string Id { get; set; } /// <summary> /// 订单时间 /// </summary> [DBField("order_time")] public DateTime OrderTime { get; set; } /// <summary> /// 订单金额 /// </summary> [DBField] public decimal? Amount { get; set; } /// <summary> /// 下单用户 /// </summary> [DBField("order_userid")] public long OrderUserid { get; set; } /// <summary> /// 订单状态(0草稿 1已下单 2已付款 3已发货 4完成) /// </summary> [DBField] public int Status { get; set; } /// <summary> /// 备注 /// </summary> [DBField] public string Remark { get; set; } /// <summary> /// 创建者ID /// </summary> [DBField("create_userid")] public string CreateUserid { get; set; } /// <summary> /// 创建时间 /// </summary> [DBField("create_time")] public DateTime CreateTime { get; set; } /// <summary> /// 更新者ID /// </summary> [DBField("update_userid")] public string UpdateUserid { get; set; } /// <summary> /// 更新时间 /// </summary> [DBField("update_time")] public DateTime? UpdateTime { get; set; } }

修改扩展实体类
  1. 修改扩展实体类，添加自定义属性
  2. 下面的扩展实体类中，查询时OrderUserRealName会被自动填充，查询SQL：select t.*, u.real_name as OrderUserRealName from ......
  3. DetailList不会被自动填充，需要手动查询
扩展实体类示例

/// <summary> /// 订单表 /// </summary> public partial class BsOrder { /// <summary> /// 订单明细集合 /// </summary> public List<BsOrderDetail> DetailList { get; set; } /// <summary> /// 下单用户姓名 /// </summary> public string OrderUserRealName { get; set; } /// <summary> /// 下单用户名 /// </summary> public string OrderUserName { get; set; } }

添加

public void Insert(SysUser info) { using (var session = DBHelper.GetSession()) { session.Insert(info); } }

批量添加

public void Insert(List<SysUser> list) { using (var session = DBHelper.GetSession()) { session.Insert(list); } }

修改

public void Update(SysUser info) { using (var session = DBHelper.GetSession()) { session.Update(info); } }

批量修改

public void Update(List<SysUser> list) { using (var session = DBHelper.GetSession()) { session.Update(list); } }

删除

public void Delete(string id) { using (var session = DBHelper.GetSession()) { session.DeleteById<SysUser>(id); } }

条件删除

using (var session = DBHelper.GetSession()) { session.DeleteByCondition<SysUser>(string.Format("id>=12")); }

查询单个记录

public SysUser Get(string id) { using (var session = DBHelper.GetSession()) { return session.FindById<SysUser>(id); } }

using (var session = DBHelper.GetSession()) { return session.FindBySql<SysUser>("select * from sys_user"); }

简单查询

using (var session = DBHelper.GetSession()) { string sql = "select * from CARINFO_MERGE"; List<CarinfoMerge> result = session.FindListBySql<CarinfoMerge>(sql); }

条件查询

public List<BsOrder> GetList(int? status, string remark, DateTime? startTime, DateTime? endTime) { using (var session = DBHelper.GetSession()) { SqlString sql = session.CreateSqlString(@" select t.*, u.real_name as OrderUserRealName from bs_order t left join sys_user u on t.order_userid=u.id where 1=1"); sql.AppendIf(status.HasValue, " and t.status=@status", status); sql.AppendIf(!string.IsNullOrWhiteSpace(remark), " and t.remark like concat('%',@remark,'%')", remark); sql.AppendIf(startTime.HasValue, " and t.order_time>=STR_TO_DATE(@startTime, '%Y-%m-%d %H:%i:%s') ", startTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); sql.AppendIf(endTime.HasValue, " and t.order_time<=STR_TO_DATE(@endTime, '%Y-%m-%d %H:%i:%s') ", endTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); sql.Append(" order by t.order_time desc, t.id asc "); List<BsOrder> list = session.FindListBySql<BsOrder>(sql.SQL, sql.Params); return list; } }

分页查询

public List<BsOrder> GetListPage(ref PageModel pageModel, int? status, string remark, DateTime? startTime, DateTime? endTime) { using (var session = DBHelper.GetSession()) { SqlString sql = session.CreateSqlString(@" select t.*, u.real_name as OrderUserRealName from bs_order t left join sys_user u on t.order_userid=u.id where 1=1"); sql.AppendIf(status.HasValue, " and t.status=@status", status); sql.AppendIf(!string.IsNullOrWhiteSpace(remark), " and t.remark like concat('%',@remark,'%')", remark); sql.AppendIf(startTime.HasValue, " and t.order_time>=STR_TO_DATE(@startTime, '%Y-%m-%d %H:%i:%s') ", startTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); sql.AppendIf(endTime.HasValue, " and t.order_time<=STR_TO_DATE(@endTime, '%Y-%m-%d %H:%i:%s') ", endTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); string orderby = " order by t.order_time desc, t.id asc "; pageModel = session.FindPageBySql<BsOrder>(sql.SQL, orderby, pageModel.PageSize, pageModel.CurrentPage, sql.Params); return pageModel.GetResult<BsOrder>(); } }

事务

public string Insert(BsOrder order, List<BsOrderDetail> detailList) { using (var session = DBHelper.GetSession()) { try { session.BeginTransaction(); order.Id = Guid.NewGuid().ToString("N"); order.CreateTime = DateTime.Now; decimal amount = 0; foreach (BsOrderDetail detail in detailList) { detail.Id = Guid.NewGuid().ToString("N"); detail.OrderId = order.Id; detail.CreateTime = DateTime.Now; amount = detail.Price * detail.Quantity; session.Insert(detail); } order.Amount = amount; session.Insert(order); session.CommitTransaction(); return order.Id; } catch (Exception ex) { session.RollbackTransaction(); Console.WriteLine(ex.Message "\r\n" ex.StackTrace); throw ex; } } }

异步查询

public async Task<List<BsOrder>> GetListPageAsync(PageModel pageModel, int? status, string remark, DateTime? startTime, DateTime? endTime) { using (var session = await DBHelper.GetSessionAsync()) { SqlString sql = session.CreateSqlString(@" select t.*, u.real_name as OrderUserRealName from bs_order t left join sys_user u on t.order_userid=u.id where 1=1"); sql.AppendIf(status.HasValue, " and t.status=@status", status); sql.AppendIf(!string.IsNullOrWhiteSpace(remark), " and t.remark like concat('%',@remark,'%')", remark); sql.AppendIf(startTime.HasValue, " and t.order_time>=STR_TO_DATE(@startTime, '%Y-%m-%d %H:%i:%s') ", startTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); sql.AppendIf(endTime.HasValue, " and t.order_time<=STR_TO_DATE(@endTime, '%Y-%m-%d %H:%i:%s') ", endTime.Value.ToString("yyyy-MM-dd HH:mm:ss")); string orderby = " order by t.order_time desc, t.id asc "; pageModel = await session.FindPageBySqlAsync<BsOrder>(sql.SQL, orderby, pageModel.PageSize, pageModel.CurrentPage, sql.Params); return pageModel.GetResult<BsOrder>(); } }

条件查询(使用 ForContains、ForStartsWith、ForEndsWith、ForDateTime、ForList 等辅助方法)

public List<BsOrder> GetListExt(int? status, string remark, DateTime? startTime, DateTime? endTime, string ids) { using (var session = DBHelper.GetSession()) { SqlString sql = session.CreateSqlString(@" select t.*, u.real_name as OrderUserRealName from bs_order t left join sys_user u on t.order_userid=u.id where 1=1"); sql.AppendIf(status.HasValue, " and t.status=@status", status); sql.AppendIf(!string.IsNullOrWhiteSpace(remark), " and t.remark like @remark", sql.ForContains(remark)); sql.AppendIf(startTime.HasValue, " and t.order_time >= @startTime ", sql.ForDateTime(startTime.Value)); sql.AppendIf(endTime.HasValue, " and t.order_time <= @endTime ", sql.ForDateTime(endTime.Value)); sql.Append(" and t.id in @ids ", sql.ForList(ids.Split(',').ToList())); sql.Append(" order by t.order_time desc, t.id asc "); List<BsOrder> list = session.FindListBySql<BsOrder>(sql.SQL, sql.Params); return list; } }

使用Lambda表达式单表查询

单表分页查询使用ToPageList替换ToList即可

public void TestQueryByLambda6() { using (var session = DBHelper.GetSession()) { SqlString<BsOrder> sql = session.CreateSqlString<BsOrder>(); string remark = "测试"; List<BsOrder> list = sql.Query() .WhereIf(!string.IsNullOrWhiteSpace(remark), t => t.Remark.Contains(remark) && t.CreateTime < DateTime.Now && t.CreateUserid == "10") .OrderByDescending(t => t.OrderTime).OrderBy(t => t.Id) .ToList(); foreach (BsOrder item in list) { Console.WriteLine(ModelToStringUtil.ToString(item)); } } }

使用Lambda表达式联表分页查询(简单的联表查询，复杂情况请使用原生SQL或原生SQL和Lambda表达式混写)

public void TestQueryByLambda7() { using (var session = DBHelper.GetSession()) { SqlString<BsOrder> sql = session.CreateSqlString<BsOrder>(); int total; List<string> idsNotIn = new List<string>() { "100007", "100008", "100009" }; List<BsOrder> list = sql.Query() .Select<SysUser>(u => u.UserName, t => t.OrderUserName) .Select<SysUser>(u => u.RealName, t => t.OrderUserRealName) .LeftJoin<SysUser>((t, u) => t.OrderUserid == u.Id) .LeftJoin<BsOrderDetail>((t, d) => t.Id == d.OrderId) .Where<SysUser, BsOrderDetail>((t, u, d) => t.Remark.Contains("订单") && u.CreateUserid == "1" && d.GoodsName != null) .WhereIf<BsOrder>(true, t => t.Remark.Contains("测试")) .WhereIf<BsOrder>(true, t => !idsNotIn.Contains(t.Id)) .WhereIf<SysUser>(true, u => u.CreateUserid == "1") .OrderByDescending(t => t.OrderTime).OrderBy(t => t.Id) .ToPageList(1, 20, out total); foreach (BsOrder item in list) { Console.WriteLine(ModelToStringUtil.ToString(item)); } } }

原生SQL和Lambda表达式混写

public void TestQueryByLambda9() { using (var session = DBHelper.GetSession()) { SqlString<BsOrder> sql = session.CreateSqlString<BsOrder>(@" select t.*, u.real_name as OrderUserRealName from bs_order t left join sys_user u on t.order_userid=u.id where 1=1"); List<BsOrder> list = sql.Where(t => t.Status == int.Parse("0") && t.Status == new BsOrder().Status && t.Remark.Contains("订单") && t.Remark != null && t.OrderTime >= new DateTime(2010, 1, 1) && t.OrderTime <= DateTime.Now.AddDays(1)) .WhereIf<SysUser>(true, u => u.CreateTime < DateTime.Now) .OrderByDescending(t => t.OrderTime).OrderBy(t => t.Id) .ToList(); foreach (BsOrder item in list) { Console.WriteLine(ModelToStringUtil.ToString(item)); } } }

,