reading data from sql table

[peterpiper]

I am attempting to retrieve data from an sql database. I have the following piece of code.
Can somebody kindly point out to me what or where I have gone wrong. When stepping
through the code with F10 it breaks when it gets to while

   SqlConnection cn = new SqlConnection(@"Server=WD\S789;Database=WinDI;User Id=;Password=;");
            SqlCommand cmd = new SqlCommand("SELECT zone,country,book,audio FROM Vand ", cn);
            cn.Open();
            SqlDataReader reader = cmd.ExecuteReader();
            {
                while (reader.Read())
                {
                    catalog(reader["zone"].ToString(), reader["country"].ToString(), reader["book"].ToString(),
                            reader["audio"].ToString());
                }
            }
            cn.Close();

Thank you

 

[jmcilhinney]

What exactly do you mean by "it breaks"? Are you saying that an exception is thrown? If so, what is the error message? If not, what actually do you mean?

 

[peterpiper]

I put a red blob alongside the line where the button code starts and pressed start debugging.
Then I press F10 (step over). When the yellow marker gets to while (reader.Read()) it then
jumps down to the curly brace just before cn.Close(); It skips the part that starts with
catalog

 

[jmcilhinney]

I put a red blob alongside the line where the button code starts and pressed start debugging.

That red blob indicates a break point. If you say that you set a break point on that line then we'll know what you mean.

Then I press F10 (step over). When the yellow marker gets to while (reader.Read()) it then
jumps down to the curly brace just before cn.Close(); It skips the part that starts with
catalog

That's not "breaking". That's doing exactly what it should. That simply means that Read returned false on the first call. If you test the value of the HasRows property of the data reader at that point, you will presumably find that it is false. It simply means that the result set from your query is empty. Your loop reads data while there's data to read so, if there's no data to read, you'll never enter the loop body.

 

[peterpiper]

Thanks JM. I checked the table and there were indeed no entries/rows. Working as it should do now. Will be more
careful in the future. As to the red blob, didn't know what it was called. Saw a c# man do it once, so copied him.
I am, as you can gather, a novice