Question

C#配置文件连接数据库了，那么登陆界面里代码怎么写？？？

Answer 1

不知道你的意思，你写了配置文件但你并未连接数据库，新建一个 连接
private static SqlConnection connection;
public static SqlConnection Connection
{
get
{
string connectionString = ConfigurationManager.ConnectionStrings["配置名字"].ConnectionString;
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();
}
return connection;
}
}

Answer 2

配置文件下，configuration节点下的connectionStrings节点下，增加节点add，例如
<add name="strConn" connectionString="连接字符串"/>

C#代码
1、项目里添加引用System.Configuration
2、类顶部添加引用using System.Configuration;

获取连接字符串代码
string connStr = ConfigurationManager.ConnectionStrings[“连接字符串名称”].ConnectionString;

这里的“连接字符串名称”指的是name的值
特别说明一下，连接字符串最好加密后再放入配置文件里