public class User { /// <summary> /// name:用于映射字段名和数据库字段不一致 /// key: /// 目前实现了Primary的定义，设置为Primary的字段update实体时，默认采用该字段为更新条件 /// isIdentity： /// 设置未true时在Insert时不会向该字段设置任何值 /// isColumn: /// 标识该字段是否在数据库存在，用于扩展User而不在sql中生成该字段 /// </summary> [Column(name: "id", key: ColumnKey.Primary, isIdentity: true, isColumn: true)] public int? Id { get; set; } [Column(name:"nick_name")] public string NickName { get; set; } [Column(name: "create_time")] public DateTime? CreateTime { get; set; } }

//在App启动时执行一次即可SessionFactory.AddDataSource(new DataSource(){ Name = "mysql", Source = () => new SqlConnection("connectionString"), SourceType = DataSourceType.SQLSERVER, UseProxy = true//使用Session的静态代理实现，记录日志，执行耗时});//获取数据库上下文using (var session = SessionFactory.GetSession("msql")){ //linq to sql}

var entity = new User(){ CreateTime=DateTime.Now, NickName="dapper",};//绝大部分接口可以设置condition已决定是否执行，支持批量更新session.From<User>().Insert(entity,condition:1>2);//查看日志var loggers = session.Loggers;

 //更新所有字段（where id=2），支持批量 session.From<User>().Update(entity); //更新部分字段 session.From<User>() .Set(a => a.NickName, "李四", condition: true)//condition为true时更新该字段 .Set(a => a.Balance, a => a.Balance + 100)//余额在原来基础增加100 .Where(a => a.Id.In(1,2,3))//将id为1，2，3的记录进行更新 .Update();

 //删除id>5||nick_name like ‘%da%‘ session.From<User>() .Where(a=>a.Id>5||a.NickName.Like("da")) .Delete();

 //查询全部字段 var user1 = session.From<User>() .Where(a=>a.Id==2) .Single(); //查询部分字段 var user2 = session.From<User>() .Where(a => a.Id == 2) .Single(s=>new { s.Id, s.NickName });

 //查询:where id in(1,2,3) var list = session.From<User>() .Where(a => a.Id.In("1,2,3".Split(‘,‘))) .Select();

 //构建动态查询，condition: true执行，多个where之间用 and 连接 var list = session.From<User>() .Where(a => a.Id.In(1, 2, 3), condition: true) .Where(a => a.NickName.Like("da"), condition: false) .Where(a => a.Id > 2 || (a.NickName.Like("da") && a.Balance > 50)) .Where("select * from user_bill where user_bill.user_id=user.id")//同样可以当作字符串拼接工具 .Select();

 /// <summary> /// 自定义函数 /// </summary> public static class MySqlFun { //这里使用泛型并不是必须的，只用函数名在数据库存在即可，泛型为了指定返回数据类型 [Function]//Dapper.Common严格区分C#函数和数据库函数，一定要用该特性标识数据库函数 public static T COUNT<T>(T column) { return default(T); } [Function] public static T MAX<T>(T column) { return default(T); } [Function] public static T DISTINCT<T>(T column) { return default(T); }

 //构建动态查询，condition: true执行，多个where之间用 and 连接 var list = session.From<Order>() .GroupBy(a => a.UserId) .Having(a => MySqlFun.COUNT(MySqlFun.DISTINCT(a.UserId)) > 10)//count(distinct(user_id))>10 .Select(s => new { s.UserId, OrderCount = MySqlFun.COUNT(1L),//这里应该返回long int， MaxFee = MySqlFun.MAX(s.TotalFee) });

 var list = session.From<Order, User>() .Join((a, b) => a.UserId == b.Id, JoinType.Inner) .GroupBy((a, b) => a.UserId) .Having((a, b) => MySqlFun.COUNT(MySqlFun.DISTINCT(a.UserId)) > 10)//count(distinct(user_id))>10 .Select((a, b) => new { a.UserId, b.NickName, OrderCount = MySqlFun.COUNT(1L),//这里应该返回long int， MaxFee = MySqlFun.MAX(a.TotalFee) });

var list = session.From<Order>() .GroupBy(a => a.UserId) .Having(a => MySqlFun.COUNT(MySqlFun.DISTINCT(a.UserId)) > 10) .Select(a => new { a.UserId, UserName=Convert.ToString("select nick_name from user where user.id=order.user_id"),//如果这个子查询返回的是int：Convert.ToInt32(sq) OrderCount = MySqlFun.COUNT(1L),//这里应该返回long int， MaxFee = MySqlFun.MAX(a.TotalFee) });

 //获取数据库上下文 ISession session = null; try { //开启事务 session.Open(true); //sql //提交事务 session.Commit(); } catch (Exception) { session?.Rollback(); throw; } finally { session?.Close(); }