.net所有项目都用的到的一个基类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace aaa.DAL
{
    public static class DBHelper
    {

        private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get 
            {
                string connectionString = "Data Source=(local);Initial Catalog=数据库; uid=用户名;pwd=密码";
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();