在Windows CE sqlconnection上使用C＃的无效连接

Question

I am creating a Smart Device project using VS2008 for a WIndows CE 6.0 device with .Net Compact Framework 3.5

Here is my code:

        string queryString = "SELECT id, name, insert_date, activity FROM dbo.[my Table]";
        StringBuilder errorMessages = new StringBuilder();

        using (SqlConnection connection = new SqlConnection("Data Source=dba;Initial Catalog=myDb;Persist Security Info=True;User ID=usern;Password=paswd"))
        {
            SqlCommand command = new SqlCommand(queryString, connection);
            try
            {
                connection.Open();
                //command.Connection.Open();
                //command.ExecuteNonQuery();
            }
            catch (SqlException ex)
            {
                for (int i = 0; i < ex.Errors.Count; i++)
                {
                    errorMessages.Append("Index #" + i + "\n" +
                        "Message: " + ex.Errors[i].Message + "\n" +
                        "LineNumber: " + ex.Errors[i].LineNumber + "\n" +
                        "Source: " + ex.Errors[i].Source + "\n" +
                        "Procedure: " + ex.Errors[i].Procedure + "\n");
                }
                Debug.WriteLine(errorMessages.ToString());

            }
        }

Mind that usernames ant table names are changed but I am getting the following errors on command.Connection.Open();

Index #0
Message: Invalid connection.
LineNumber: 0
Source: .Net SqlClient Data Provider
Procedure: ConnectionOpen (Invalid Instance()).

Why and how to fix it? The device easly pings the server machine if that is useful.

Answer 1

at place of command.Connection.Open(); use connection.open() and after execute query close the connection...

Answer 2

是的，在创建命令对象之前打开连接，您将不需要关闭连接，因为它在using {}内部