一、Dapper基本操作

参考资料：Cooper Liu 毒逆天

一、Dapper安装

　　添加引用-->NuGet管理-->搜索Dapper-->安装

二、新建表　

--创建一个员工表
create table Employee
(
    Em_Id int identity(1,1) primary key,
    Em_Name varchar(50) not null,
    Em_Age int default(18) not null
)

--部门表
Create Table Department
(
    Depart_Id int identity(1,1) primary key,
    Depart_Name varchar(20) not null,
)

--员工所属部门关系表
Create table EmployeePartment
(
    EP_Id int identity(1,1) primary key,
    Em_Id int not null,
    Depart_Id int not null
)

三、新建实体类

　　实体类属性要与数据库中的字段名称对应

/// <summary>
    /// 生成Employee实体，注意类属性与表字段要一一对应
    /// </summary>
    public class Employee
    {
        public int Em_Id { get; set; }
        public string Em_Name { get; set; }

        public int Em_Age { get; set; }
    }
    /// <summary>
    /// 生成部门Department实体
    /// </summary>
    public class Department
    {
        public int Depart_Id { get; set; }
        public string Depart_Name { get; set; }
    }

    /// <summary>
    /// 生成部门员工所属部门对应关系
    /// </summary>
    public class EmployeePartment
    {
        public int EP_Id { get; set; }
        public int Em_Id { get; set; }
        public int Depart_Id { get; set; }
    }

四、插入操作

　　Dapper支持单个插入，也支持批量插入(Bulk)，支持存储过程进行插入操作。

/// <summary>
        /// 声明object类型可用单个对象时插入单对象，也可批量BulkInsert插入(只要实现IEnumable接口)
        /// </summary>
        /// <param name="obj"></param>
        private static void InsertEmployee(Object obj)
        {
            using (var conn = GetConnection())
            {
                string sql = "insert into employee values (@Em_Name,@Em_Age)";
                int result = conn.Execute(sql, obj);
            }
        }

        /// <summary>
        /// 插入部门操作
        /// </summary>
        /// <param name="depart"></param>
        private static void InsertDepartment(object depart)
        {
            CommandDefinition command = new CommandDefinition("insert into department values (@Depart_Name)", depart);
            using (var conn=GetConnection())
            {
                conn.Execute(command);
            }

        }

        /// <summary>
        /// 生成sqlConnection对象。返回IDbConnection.
        /// </summary>
        /// <returns></returns>
        private static IDbConnection GetConnection()
        {
            var conn = new SqlConnection(connstr);
            return conn;
        }

　　示例中使用了conn.Execute()方法，该方法两个种形式的重载。

　　　　1、public static int Execute(this IDbConnection cnn, CommandDefinition command);

　　　　2、public static int Execute(this IDbConnection cnn, string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null);

　　　　虽说是两种形式，其实质是CommandDefinition对重载的第二个方法条件进行了封闭。由CommandDefinition构造函数定义可以看到对应关系。

　　　　 public CommandDefinition(string commandText, object parameters = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null, CommandFlags flags = CommandFlags.Buffered);

　　 Execute是IDbConnection的扩展方法，所以conn可以直接调用。

五、删除操作

　　Dapper支持sql语句删除操作，也支持存储过程删除操作

//此处为方法调用
 //Ado.net方法删除
 DeleteEmployeeById();

UseCommandDeleteEmployeeUseById();

//存储过程删除
ProcDeleteEmployeeById();

//此处为方法实现
 /// <summary>
        /// 根据ID删除对应Employee
        /// </summary>
        /// <param name="id">待删除的EmployeeId</param>
        private static void DeleteEmployeeById(int id)
        {
            using (var conn=GetConnection())
            {
               int result= conn.Execute("delete from Employee where EM_Id=@id", new { @id = id });
            }
        }

        /// <summary>
        /// 使用Command形式删除操作
        /// </summary>
        /// <param name="id">待删除的Employee的ID</param>
        private static void UseCommandDeleteEmployeeUseById(int id)
        {
            var command = new CommandDefinition("delete from Employee where Em_Id=@Eid", new { @Eid = id }, null, null, CommandType.Text,CommandFlags.None);

            using (var conn=GetConnection())
            {
                int result = conn.Execute(command);
            }
        }
        /// <summary>
        /// 使用存储过程形式删除Employee
        /// </summary>
        /// <param name="id">待删除的Employee</param>
        private static void ProcDeleteEmployeeById(int id)
        {
            using (var conn = GetConnection())
            {
               int result= conn.Execute("pr_delete_employee", new { @id = id },null,null,CommandType.StoredProcedure);
            }
        }

　　删除示例中也是使用conn.Execute()方法进行操作。

六、更新操作

　　操作同新增、删除同样使用conn.Execute()方法进行。

//方法调用
  UpdateEmployeeName(, "新名称");

  UseCommandUpdateEmployee(, );

  ProcUpdateEmployeeName(, "旧名称");
//方法实现

        /// <summary>
        /// 更新指定ID名称为新值
        /// </summary>
        /// <param name="eid">Employee的Id</param>
        /// <param name="name">新的employee名称</param>
        private static void UpdateEmployeeName(int eid, string name)
        {
            using (var conn=GetConnection())
            {
               int result= conn.Execute("update Employee set Em_Name=@name where Em_Id=@id", new { @name = name, @id = eid });
            }
        }

        /// <summary>
        /// 使用Command形式更新Employee信息
        /// </summary>
        /// <param name="eid">待更新的EmployeeId</param>
        /// <param name="Age">Age新值</param>
        private static void UseCommandUpdateEmployee(int eid, int Age)
        {
            var command=new CommandDefinition("update Employee set Em_Age=@age where em_Id=@eid",new{@age=Age,@eid=eid},null,null,CommandType.Text,CommandFlags.None);
            using (var conn=GetConnection())
            {
                int result = conn.Execute(command);
            }
        }

        /// <summary>
        /// 更新指定ID名称为新值
        /// </summary>
        /// <param name="eid">Employee的Id</param>
        /// <param name="name">新的employee名称</param>
        private static void ProcUpdateEmployeeName(int eid, string name)
        {
            using (var conn = GetConnection())
            {
                var p = new DynamicParameters();
                p.Add("@id", eid);
                p.Add("@name", name);
                int result = conn.Execute("pr_update_employee", new {  id = eid,name = name },null,null,CommandType.StoredProcedure));
            }
        }

七、查找操作　　　

//简单查询
            Employee employee = GetEmployeeById();
            if (employee != null)
            {
                Console.WriteLine("ID为5的员工已找到名称:" + employee.Em_Name);
            }

            //子查询
            List<Employee> list_employees = GetEmployeesByPartId();
            Console.WriteLine("共找到{0}记录:", list_employees.Count);
            for (int i = ; i < list_employees.Count; i++)
            {
                Console.Write(list_employees[i].Em_Name + ",");
            }

            //多返回值
            GetMutile();
/// <summary>
        /// 根据ID查找EmpolyeeID 支持ADO语句和存储过程
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        private static Employee GetEmployeeById(int id)
        {
            Employee employee = new Employee();
            using (var conn = GetConnection())
            {
                employee = conn.Query<Employee>("select * from employee where Em_Id=@id", new { id = id }).FirstOrDefault();

            }

            //CommandDefinition command = new CommandDefinition("select * from employee wehre em_id=@id");

            //using (var conn = GetConnection())
            //{
            //    employee = conn.Query<Employee>(command).FirstOrDefault();

            //}

            return employee;
        }

        /// <summary>
        /// 子查询
        /// </summary>
        /// <param name="partid"></param>
        /// <returns></returns>
        private static List<Employee> GetEmployeesByPartId(int partid)
        {
            List<Employee> employees = new List<Employee>();

            CommandDefinition command = new CommandDefinition("select * from employee where em_id in (select em_id from  EmployeePARTMENT where Depart_Id=@id) ", new { id = partid });

            using (var conn = GetConnection())
            {
                employees = conn.Query<Employee>(command).ToList();
            }
            return employees;
        }

        /// <summary>
        /// 多返回值查询
        /// </summary>
        private static void GetMutile()
        {
            string sql = @"select * from [Employee];
                     select  *  from [Department]";
            CommandDefinition command = new CommandDefinition(sql);

            using (var conn = GetConnection())
            {
                var muitle = conn.QueryMultiple(sql);
                //var muitle=conn.QueryMultiple(command);
                if (!muitle.IsConsumed)
                {
                    //强类型读取
                    //var employees = muitle.Read<Employee>();
                    //var deparements = muitle.Read<Department>();

                    //动态类型读取
                    var employees = muitle.Read();
                    var deparements = muitle.Read();

                    foreach (var item in employees)
                    {
                        Console.WriteLine(item.Em_Name + ":" + item.Em_Age.ToString());
                    }

                    Console.WriteLine();

                    foreach (var item in deparements)
                    {
                        Console.WriteLine(item.Depart_Name + ":" + item.Depart_Id);
                    }

                }
            }
        }

八、总结

　　使用Dapper进行增删改查、存储过程调用、多表值返回操作。