Ado.Net 实体类、数据连接类、数据访问类

java获取数据库表字段。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Carc.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+"\t"+data.Name+"\t"+data.Oil+"\t"+data.Powers+"\t"+data.Price);//foreach中不能改变元素的结构//if (data.Code == "c001")//{//    list.Remove(data);//}
            }Console.ReadLine();}}
}