c - if SqlConnection C# 检查连接打开、关闭

Question

我的代码不想返回关闭连接。如果我没有太多知识，我就无法使用它们。

 private void button1_Click(object sender, EventArgs e)
    {
        string connectionString = GetCString();

        using (SqlConnection connection = new SqlConnection(connectionString))


            if (connection.State == ConnectionState.Open)
            {
                connection.Open();
                Logger.getS().info_warning("Conexão Sucedida");
                Logger.getS().info_warning("DataSource : " + connection.DataSource);
                Logger.getS().info_warning("Banco De Dados : " + connection.Database);
                Logger.getS().info_warning("Versão do SQL : " + connection.ServerVersion);
                Logger.getS().info_warning("Status : " + connection.State);

                {

                }

            }
              else
              {

                  Logger.getS().info_erro("SqlConnection Não foi possivel connectar.");
                  Logger.getS().info_erro(" Status da Conexão : " + connection.State);


              }

        }

Answer 1

当您创建新连接时，最初它总是关闭的。然后，您需要打开它。但是，您需要在打开连接之前检查连接是否打开。

此后，在您的情况下，此条件将永远不会true:

if (connection.State == ConnectionState.Open)

此外，您不需要检查连接的状态。如果连接失败，则会抛出异常。您只需打开一个连接并确保它正常工作或抛出异常。

应该是这样的:

try 
{
    string connectionString = GetCString();

    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        connection.Open();
        Logger.getS().info_warning("Conexão Sucedida");
        Logger.getS().info_warning("DataSource : " + connection.DataSource);
        Logger.getS().info_warning("Banco De Dados : " + connection.Database);
        Logger.getS().info_warning("Versão do SQL : " + connection.ServerVersion);
        Logger.getS().info_warning("Status : " + connection.State);
    }
}
catch (Exception ex)
{ 
    Logger.getS().info_error("SqlConnection Não foi possivel connectar.");
    Logger.getS().info_error("SqlConnection exception message: " + ex.Message + "\r\n" + ex.StackTrace);
}

P.S.您可以将 info_error、info_warning 等实现为 (string message, params string[] args)并使用String.Format。这可能会更方便:

Logger.getS().info_warning("Versão do SQL: {0}", connection.ServerVersion);