Dapper的使用

Dapper是一款轻量级ORM工具（Github）。如果你在小的项目中，使用Entity Framework、NHibernate 来处理大数据访问及关系映射，未免有点杀鸡用牛刀。你又觉得ORM省时省力，这时Dapper 将是你不二的选择。

为什么选择Dapper

1. 轻量。只有一个文件（SqlMapper.cs），编译完成之后只有120k(好象是变胖了)
2. 速度快。Dapper的速度接近与IDataReader，取列表的数据超过了DataTable。
3. 支持多种数据库。Dapper可以在所有Ado.net Providers下工作，包括sqlite, sqlce, firebird, oracle, MySQL, PostgreSQL and SQL Server
4. 可以映射一对一，一对多，多对多等多种关系。
5. 性能高。通过Emit反射IDataReader的序列队列，来快速的得到和产生对象，性能不错。
6. 支持FrameWork2.0，3.0，3.5，4.0，4.5

首先从

        //获取一个连接字符串
        private static readonly string constr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
        //写一个打开数据库操作
        public static IDbConnection GetDbConnection()
        {
            IDbConnection connection = new SqlConnection(constr);
            if (connection.State == ConnectionState.Closed)
            {
                connection.Open();
            }
            return connection;
        }

在数据访问层的展示

记得引用 using Dapper;

 
//简单查询
public static List<UserInfo> Show()
        {
            using (IDbConnection connection =DBHelper.GetDbConnection())
            {
                return connection.Query<UserInfo>("查询语句").ToList();
            }
        }

//简单添加
public static int Insert(Person person)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Execute("insert into Person(Name,Remark) values(@Name,@Remark)", person);
    }
}

//删除操作
public static int Delete(Person person)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Execute("delete from Person where id=@ID", person);
    }
}

public static int Delete(List<Person> persons)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Execute("delete from Person where id=@ID", persons);
    }
}

//修改操作
public static int Update(Person person)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Execute("update Person set name=@name where id=@ID", person);
    }
}

public static int Update(List<Person> persons)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Execute("update Person set name=@name where id=@ID", persons);
    }
}

/// <summary>
/// 无参查询所有数据
/// </summary>
/// <returns></returns>
public static List<Person> Query()
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
    return connection.Query<Person>("select * from Person").ToList();
    }
}

/// <summary>
/// 查询指定数据
/// </summary>
/// <param name="person"></param>
/// <returns></returns>
public static Person Query(Person person)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        return connection.Query<Person>("select * from Person where id=@ID",person).SingleOrDefault();
}
}

//查询的In操作
/// <summary>
/// In操作
/// </summary>
public static List<Person> QueryIn()
{
    using (IDbConnection connection = new 
SqlConnection(connectionString))
    {
        var sql = "select * from Person where id in @ids";
        //参数类型是Array的时候，dappper会自动将其转化
        return connection.Query<Person>(sql, new { ids = new int[2] { 1, 2 }, }).ToList();
    }
}

public static List<Person> QueryIn(int[] ids)
{
    using (IDbConnection connection = new SqlConnection(connectionString))
    {
        var sql = "select * from Person where id in @ids";
        //参数类型是Array的时候，dappper会自动将其转化
        return connection.Query<Person>(sql, new { ids }).ToList();
    }
}

控制器展示

//查询数据
 public IEnumerable<UserInfo> Show(int iPageIndex = 1, int iPageSize = 2)
        {
            List<UserInfo> list = new List<UserInfo>();
            list = dal.Show();
 　　　　　　//由此实现一个分页操作
            list=  list.Skip((PageSize-1) * PageIndex).Take(PageSize).ToList();return list;
        }

 public int Del(int id)
        {
            return dal.Delete(id);
        }

下面是另一种写法

       //数据库连接
        string str = "";

        //添加
        [HttpPost]
        public int Add(ModelInfo mf)
        {
            using (SqlConnection conn = new SqlConnection(str))
            {
                string sql = $"insert into Goods values ('{mf.Name}','{mf.Pwd}')";
                return conn.Execute(sql, mf);
            }
        }

        //显示
        [HttpGet]
        public List<ModelInfo> Show()
        {
            using (SqlConnection conn = new SqlConnection(str))
            {
                ModelInfo mf = new ModelInfo();
                string sql = $"select * from Goods";
                return conn.Query<ModelInfo>(sql, mf).ToList();
            }
        }
        //查询
        [HttpGet]
        public List<ModelInfo> Select(string name)
        {
            using (SqlConnection conn = new SqlConnection(str))
            {
                string sql = $"select * from Goods where Name like '%{name}%'";
                return conn.Query<ModelInfo>(sql, name).ToList();
            }
        }

        //删除
        //vs的BUG 删除不用Get出不来
        [HttpGet]
        public int Del(string id)
        {
            using (SqlConnection conn = new SqlConnection(str))
            {
                string sql = $"delete Goods where ID = {id}";
                return conn.Execute(sql, id);
            }
        }

        //修改
        [HttpPut]
        public int Upd(ModelInfo mf)
        {
            using (SqlConnection conn = new SqlConnection(str))
            {
                string sql = $"update Goods set Pwd = '{mf.Pwd}' where ID = {mf.ID} ";
                return conn.Execute(sql, mf);
            }
        }