I cant get sql read to work.

Question

User-424182210 posted

In my code I can open a sql channel ok.

However I cant get it to read a table with a username and password field.

I get username not a valid object error.

           
            string connectionString = @"Server = (localdb)\MSSQLLocalDB; connect timeout=30; database=Database1; Integrated Security = false; ";


            SqlConnection connection = new SqlConnection();
            
                connection.ConnectionString = connectionString;

                try
                {
                    connection.Open();
                }
                catch (Exception err)
                {
                    Console.WriteLine(err.ToString());
                }
            
  





            try
            {
                SqlDataReader myReader = null;
                SqlCommand myCommand2 = new SqlCommand(
                "SELECT * from [username];", connection);



                myReader = myCommand2.ExecuteReader();
                while (myReader.Read())
                {
                    TextBox1.Text = myReader["username"].ToString();
                }
            }
            catch (Exception er)
            {
                Console.WriteLine(er.ToString());
            }

Answer 1

User2103319870 posted

 while (myReader.Read())

{

TextBox1.Text = myReader["username"].ToString();

}

Ensure that the columnname which you get from username table is equal to what you used in above code

Answer 2

User-2057865890 posted

Hi 75577557,

SqlDataReader objects allow you to read data in a fast forward-only manner. You obtain data by reading each row from the data stream. 

HasRows enables you to determine if the DataReader has returned any results before reading from it.

As a2h said, ensure that the columnname which you get from username table is equal to what you used in above code

Take a look at the following code snippets.

class Program
    {
        static void Main(string[] args)
        {
            SimpleRead();
        }
        public static void SimpleRead()
        {
            // declare the SqlDataReader, which is used in
            // both the try block and the finally block
            SqlDataReader rdr = null;

            // create a connection object
            SqlConnection conn = new SqlConnection("Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI");

            // create a command object
            SqlCommand cmd = new SqlCommand("select * from Customers", conn);

            try
            {
                // open the connection
                conn.Open();

                // 1. get an instance of the SqlDataReader
                rdr = cmd.ExecuteReader();

                // print a set of column headers
                Console.WriteLine("Contact Name             City                Company Name");
                Console.WriteLine("------------             ------------        ------------");

                // 2. print necessary columns of each record

                if (rdr.HasRows)
                {
                    while (rdr.Read())
                    {
                        // get the results of each column
                        string contact = (string)rdr["ContactName"];
                        string company = (string)rdr["CompanyName"];
                        string city = (string)rdr["City"];

                        // print out the results
                        Console.Write("{0,-25}", contact);
                        Console.Write("{0,-20}", city);
                        Console.Write("{0,-25}", company);
                        Console.WriteLine();
                    }
                }
                else
                {
                    Console.WriteLine("No rows found.");
                }
            }
            finally
            {
                // 3. close the reader
                if (rdr != null)
                {
                    rdr.Close();
                }

                // close the connection
                if (conn != null)
                {
                    conn.Close();
                }
            }
        }
    }

Best Regards,

Chris Zhao