修改 connection string during install process

public bool modifyConnectionString(string ServerName, string DBName, string AdminName, string AdminPwd, string targetSite)
{

string connectionString = string.Empty;

if (AdminName != string.Empty && AdminPwd != string.Empty)
connectionString = String.Format("Data Source={0};initial catalog={1};id={2};password={3}", ServerName, DBName, AdminName, AdminPwd);
else
connectionString = String.Format("Integrated Security=true;Data Source={0};initial catalog={1}", ServerName, DBName);
try
{
// Get the configuration object for a Web application
// running on the local server.
System.Configuration.Configuration config = WebConfigurationManager.OpenWebConfiguration("/" + targetSite)
as System.Configuration.Configuration;

// Get the appSettings.
ConnectionStringSettings settings = new ConnectionStringSettings();
settings.Name = "connectionString1";
settings.ConnectionString = connectionString;
MessageBox.Show(connectionString);
config.ConnectionStrings.ConnectionStrings.Clear();
config.ConnectionStrings.ConnectionStrings.Add(settings);
config.Save();
return true;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return false;
}

}