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

namespace zsg
{
    public partial class Form1 : Form
    {
        private SqlConnection dbConnection;
        public Form1()
        {
            InitializeComponent();
        }
        //连接数据库
        private void button1_Click(object sender, EventArgs e)
        {
            string strConn;
            try
            {
                dbConnection = new SqlConnection();
                strConn = "DataSource=localhost;";
                strConn += "Initial Catalog=lunwen;";
                strConn += "Integrated Security=Ture";
                dbConnection.ConnectionString = strConn;
                //dbConnection.Open();
                label4.Text = "连接成功";
            }
            catch (Exception e3)
            {
                MessageBox.Show(e3.Message);
            }
        }
    }
}
问题在哪？谢谢。

关于接口的作用，谁能帮我讲讲的，谢谢了

是不是只能用方法，却不能知道它的方法体啊？