简单的连接数据库

/**/ ////App.config 文件内容

<? xml version = " 1.0 "  encoding = " utf-8 "   ?>
< configuration  >
   < connectionStrings  >
     < add name  = " OLEDB "  connectionString = " Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:C#BoyangMISinDebugBoyangDB.mdb;Persist Security Info=True " />
   </ connectionStrings >
</ configuration >

/**/ Connectionstr.cs 类
using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Configuration;
namespace  BoyangMIS
... {
    class Connectionstr
    ...{
        public static string ConnectionString = ConfigurationManager.ConnectionStrings["OLEDB"].ConnectionString;
    }
}
/**/ //实现
string  connstr  =  Connectionstr.ConnectionString;

   OleDbConnection oleconn = new OleDbConntion(connstr);