Ado.Net 实体类、数据连接类、数据访问类

建文件夹：定义数据连接类、数据访问类、实体类

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace 实体类_数据访问类_数据连接类
{
    //数据连接类
    class DataConnection
    {
        private static string connstr = "server=.; database=mydb; user=sa; pwd=ray;";
        public static SqlConnection Conn
        {
            get { return new SqlConnection(connstr); }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace 实体类_数据访问类_数据连接类
{
    //数据访问类
    class CarData
    {
        private SqlConnection _conn;    //连接对象
        private SqlCommand _cmd;
        private SqlDataReader _dr;

        public CarData()     //构造函数：初始化对象
        {
            _conn = DataConnection.Conn;
            _cmd = _conn.CreateCommand();
        }

        /// <summary>
        /// 查询Car表中指定数据
        /// </summary>
        /// <param name="name">编号</param>
        /// <returns>List<T></returns>
        public List<Car> Select(string name)
        {
            _cmd.CommandText = "select *from Car where Name like @name";
            _cmd.Parameters.Clear();
            _cmd.Parameters.AddWithValue("@name","%"+name+"%");
            _conn.Open();
            _dr = _cmd.ExecuteReader();

            List<Car> list = new List<Car>();  //实例化List<Car>

            if (_dr.HasRows)
            {
                while (_dr.Read())
                {
                    Car c = new Car();    //实例化Car
                    c.Code = _dr["Code"].ToString();
                    c.Name = _dr["Name"].ToString();
                    c.Oil = Convert.ToDouble(_dr["Oil"]);
                    c.Powers = Convert.ToInt32(_dr["Powers"]);
                    c.Price = Convert.ToDecimal(_dr["Price"]);

                    list.Add(c);     //将查询出的数据放入list中
                }
            }

            _conn.Close();

            return list;
            
        }               

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 实体类_数据访问类_数据连接类
{
　　//实体类
    class Car
    {
        private string _code;

        public string Code
        {
            get { return _code; }
            set { _code = value; }
        }
        private string _name;

        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }
        private double _oil;

        public double Oil
        {
            get { return _oil; }
            set { _oil = value; }
        }
        private int _powers;

        public int Powers
        {
            get { return _powers; }
            set { _powers = value; }
        }
        private decimal _price;

        public decimal Price
        {
            get { return _price; }
            set { _price = value; }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 实体类_数据访问类_数据连接类
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("请输入要查询的名称：");
            string name = Console.ReadLine();

            CarData dd = new CarData();
            List<Car> list = dd.Select(name);

            //使用foreach遍历集合
            foreach (Car data in list)
            {
                Console.WriteLine(data.Code+"	"+data.Name+"	"+data.Oil+"	"+data.Powers+"	"+data.Price);
            
                //foreach中不能改变元素的结构
                //if (data.Code == "c001")
                //{
                //    list.Remove(data);
                //}
            }

            Console.ReadLine();
        }
    }
}