vs 2003 中配置文件 ：
vs 2005 中配置文件 ：
<appSettings>
<add key="ConnectionString" value="Server=210.1.1.22;database=erpuse;uid=sa;pwd=;"></add>
</appSettings>
vs 2003中調用：
SqlConnection cn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]);
vs 2005中調用：
public static string conStr = ConfigurationManager.AppSettings["ConnectionString"].ToString();
vs 2005 中配置文件：
<connectionStrings>
<add name="book" connectionString="Server=210.1.1.22;database=lvwz;uid=sa;pwd=;" providerName="System.Data.SqlClient"/>
</connectionStrings>
調用：
public static SqlConnection con()
{//数据库连接类
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["book"].ConnectionString);
return con;
}