Code Analysis- Do not dispose objects multiple times

Question

When i analyzed my code from Visual Studio 2013 some warnings appear that "Do not dispose objects multiple times " it also stated that object conn disposed multiple times in object but as i know if i did not use this object multiple times in object than i cant achieve my goals. so kindly tell me how i can remove this warning ?

here is my code :

private void GetData()
        {
            DataTable dt = new DataTable();
            _connString = ConfigurationManager.AppSettings["connString"];
            using (SqlConnection conn = new SqlConnection(_connString))
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand("select * from ref_CourseRegistration_Users", conn);
                cmd.CommandType = CommandType.Text;
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                conn.Close();
                if (ds.Tables[0].Rows.Count > 0)
                {
                    grdUsers.DataSource = ds;
                    grdUsers.DataBind();
                }
            }
        }

here is screenshot of my analysis :

Answer 1

Here if you are using the using statement

using (SqlConnection conn = new SqlConnection(_connString))

no need to close the connection again so conn.Close(); is not required.

It'll automatically dispose the object.

Answer 2

When you are opening a connection in using block, the using block will automatically call the Dispose() method while leaving the using block scope.

So, conn.Close(); is not required in your code.