操作数据类m

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

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
//接收用户输入的查询条件
Console.WriteLine("请输入要查询的汽车代号：");
string code = Console.ReadLine();

//造连接对象
SqlConnection conn = new SqlConnection("server=.;database=mydb;user=sa;pwd=123");

//造命令对象
SqlCommand cmd = conn.CreateCommand();

//给命令对象一条SQL语句
cmd.CommandText = "select * from Car where Code=@code";
cmd.Parameters.AddWithValue(@code,code);
//改变量绑定参数
cmd.Parameters.Clear();//清除绑定的变量
cmd.Parameters.AddWithValue("@code", code);
//cmd.Parameters.AddWithValue("@name",name);

//打开连接
conn.Open();

//执行SQL语句
SqlDataReader dr = cmd.ExecuteReader();

//读取数据
if (dr.HasRows)
{
while (dr.Read())
{
Console.WriteLine(dr[0] + "--" + dr[1]);

}
}
else
{
Console.WriteLine("没有查到相应的数据");
}
Console.WriteLine("1是删除2是修改3是添加");
int a = int.Parse(Console.ReadLine());
dr.Close();
if (a == 1)
{
cmd.CommandText = "delete from Car where Code=@code";
cmd.Parameters.Clear();//清除绑定的变量
cmd.Parameters.AddWithValue("@code", code);

cmd.ExecuteNonQuery();
Console.WriteLine("删除成功！");
}

else if (a == 2)
{
int m = 0;
while (m < 1)
{
Console.WriteLine("你可以修改的内容为Powers/Exhaust/Price,请输入你要修改的列");
string b = Console.ReadLine();
Console.WriteLine("修改为");
string c = Console.ReadLine();
if (b == "Powers")
{
cmd.CommandText = "update Car set Powers=@powers where Code='" + code + "'";
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("@powers", c);

cmd.ExecuteNonQuery();
Console.WriteLine("修改成功");
}
else if (b == "Exhaust")
{
cmd.CommandText = "update Car set Exhaust=@exhaust where Code='" + code + "'";
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("@exhaust", c);

cmd.ExecuteNonQuery();
Console.WriteLine("修改成功");
}
else if (b == "Price")
{
cmd.CommandText = "update Car set Price=@price where Code='" + code + "'";
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("@Price", c);

cmd.ExecuteNonQuery();
Console.WriteLine("修改成功");
}
else
{
Console.WriteLine("输入错误");
}

m++;
Console.WriteLine("是否继续修改内容？是1不是2");
int n = int.Parse(Console.ReadLine());
if (n == 1)
{
m--;
}
else
{
Console.WriteLine("你所修改的内容已全部修改完毕");
}

}
}

else if (a == 3)
{
Console.WriteLine("请输入添加的内容");
Console.WriteLine("请输入添加的代号");
string Code = Console.ReadLine();

Console.WriteLine("请输入添加的名字");
string Name = Console.ReadLine();

Console.WriteLine("请输入添加的brand");
string Brand = Console.ReadLine();

Console.WriteLine("请输入添加的time");
string Time = Console.ReadLine();
Console.WriteLine("请输入添加的Oil");
string Oil = Console.ReadLine();
Console.WriteLine("请输入添加的powers");
string Powers = Console.ReadLine();
Console.WriteLine("请输入添加的exhaust");
string Exhaust = Console.ReadLine();
Console.WriteLine("请输入添加的price");
string Price = Console.ReadLine();

Console.WriteLine("请输入添加的pic");
string Pic = Console.ReadLine();

dr.Close();

cmd.CommandText = "insert into Car values('" + Code + "','" + Name + "','" + Brand + "','" + Time + "','" + Oil + "','" + Powers + "','" + Exhaust + "','" + Price + "','" + Pic + "')";
cmd.ExecuteNonQuery();
Console.WriteLine("添加成功！");
}
else
{
Console.WriteLine("输入有误");
}

//关闭连接
conn.Close();

Console.ReadLine();
}