xt

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;

namespace WindowsFormsApplication6
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

       private void button1_Click(object sender, EventArgs e)
        {

            SqlConnection x = new SqlConnection("Data Source=.;Initial Catalog=XT;Integrated Security=True");//创建连接对象
            x.Open();//打开链接

           //从表中提取数据
            //string str = string.Format("select City from xt");
           //DataTable y = new DataTable();//创建一个数据表
            //SqlDataAdapter z = new SqlDataAdapter(str, x);//利用str字符串和x数据库连接对象创建适配器
            //z.Fill(y);//将适配器内的数据内容填充到数据表中

           //插入
           // string str = string.Format("insert into xt(ID, LastName, FirstName, Address, City) values (12, '林玲', '林笨笨','2号','商城')");
            //string str = string.Format("insert into xt (ID, LastName, City) values (22, '小梅', '忘了')");

           //删除
            int ID = ;
            string str = string.Format("delete from xt where ID = " + ID + "");

            SqlCommand n = new SqlCommand(str, x);//创建Command对象，两个参数：需要执行的str，数据连接对象x
            int i = n.ExecuteNonQuery();//执行命令（多用于执行增加、删除、修改数据，返回受影响的行数）

           MessageBox.Show("成功！");
        }
    }
}