一个非常不错的数据库连接

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data.SqlClient;using System.Data;namespace WindowsFormsApplication1{class DBClass{//两个字段，一个属性，两个方法//第一个字段：连接字符创private const string conString = @"Data Source=.;Initial Catalog=Borad;Integrated Security=True";//第二个字段：连接字段private SqlConnection _Connection;//一个属性，即连接的属性public SqlConnection Connection{get{if (_Connection == null)_Connection = new SqlConnection(conString);return _Connection;}}//第一个方法：打开连接public void OpenConnection(){if (Connection.State == ConnectionState.Closed){Connection.Open();}elseif(Connection.State==ConnectionState.Broken){Connection.Close();Connection.Open();}}//第二个方法：关闭连接public void CloseConnection(){if (Connection.State == ConnectionState.Open|| Connection.State == ConnectionState.Broken){Connection.Close();}}}}