数据库连接,ACCESS,SQL.

1.ACCESS 连接

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

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

        private void btnConnect_Click(object sender, EventArgs e)
        {
            try
            {
                //新建连接对象conn
                OleDbConnection conn = new OleDbConnection();

                //构造数据库连接字符串
                //必须使用Server.MapPath方法将相对路径转化为服务器
                //上的绝对路径
                string connStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=";
                connStr += @"Data\Student.mdb";

                //输出目前的连接字符串，查看Server.MapPath的作用
                MessageBox.Show("当前连接字符串为：\n" + connStr + "\n");

                //指定conn对象的连接字符串属性
                conn.ConnectionString = connStr;

                conn.Open();

                //测试是否打开连接
                if (conn.State == ConnectionState.Open)
                {
                    MessageBox.Show("成功打开数据库连接");
                }


                //关闭连接
                conn.Close();

                //测试是否关闭连接
                if (conn.State == ConnectionState.Closed)
                {
                    MessageBox.Show("成功关闭数据库连接");
                }
            }
            //捕获异常
            catch (Exception ex)
            {
                MessageBox.Show("数据库连接失败，可能的原因是：\n" + ex.Message);
            }
        }
    }
}

2.SQL 连接

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

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

        private void btnConnect_Click(object sender, EventArgs e)
        {
            try
            {
                SqlConnection conn = new SqlConnection();
                conn.ConnectionString = 
                  "Data Source=(local);user id=sa;password=1234;initial catalog=students;";

                conn.Open();

                if(conn.State == ConnectionState.Open)
                {
                    MessageBox.Show("连接已经打开");
                }


                conn.Close();

                if(conn.State == ConnectionState.Closed)
                {
                    MessageBox.Show("连接已经关闭");
                }
            }
            catch(Exception ex)
            {
                MessageBox.Show("数据库连接失败，可能的原因是" + ex.Message);
            }

        }
    }
}