修改数据库连接串

最基本的Web.Config
<?xml version="1.0" encoding="utf-8" ?>
<configuration> 
<appSettings> 
<add key="y" value="this is Y"/> 
</appSettings>
</configuration>

读：System.Configuration.ConfigurationManager.AppSettings[“y”];
加：
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
AppSettingsSection app = config.AppSettings;
app.Settings.Add("x", "this is X");
config.Save(ConfigurationSaveMode.Modified);
修改：
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
AppSettingsSection app = config.AppSettings;
//app.Settings.Add("x", "this is X");
app.Settings["x"].Value = "this is not Y";config.Save(ConfigurationSaveMode.Modified);
删除：
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
AppSettingsSection app = config.AppSettings;
app.Settings.Remove("x");
config.Save(ConfigurationSaveMode.Modified);