Returning 2-dimensional array via C#

Question

I'm getting content from a database and returning it for Ajax processing via Javascript. Pretty simple stuff. The issue here is that I can't seem to find a good way to loop through the data and the MSDN documentation is obscenely poor for its odbcreader methods.

using (OdbcCommand com = new OdbcCommand("SELECT * FROM pie_data WHERE Pie_ID = ?",
 con)) {
  if (Request.Form["reference_id"] == "") {
    returnError();
  } else {
    com.Parameters.AddWithValue("", Request.Form["reference_id"]);
    com.ExecuteNonQuery();
    using (OdbcDataReader reader = com.ExecuteReader()) {
      string finalstring = "";
      while (reader.Read()) {
        if(reader.HasRows) {
          finalstring = reader.GetString(9) + ",";
          for (int i = 0; i <= 8; i = i + 1) {
            finalstring = finalstring + reader.GetValue(i).ToString() + ",";
          }
          finalstring = finalstring + "|";
          reader.NextResult();
        }
      }
      if (finalstring != "") {
        finalstring = finalstring.Remove(finalstring.Length -1, 1);
        Response.Write(finalstring);
      }
    }
    noredirect = 1;
  }
}

However, here is the sample output:

00001,0,Pie Johnson,piesaregreat@yum.com,,,10/7/2010 12:00:00 AM,Bakery,N/A,N/A,

As you can see, the second deliminator is not appearing at all, when it really should. Also, this query, when run in heidisql, returns a good number of rows, not just this one result. Once I have it passed to the Javascript, I can figure it out since I have much more experience with that and I've actually done this before via PHP.

Answer 1

I would use a DataTable and a DataAdapter :

String finalString;
var tblPieData = new DataTable();
using(var con = new OdbcConnection(connectionString))
using (OdbcDataAdapter da = new OdbcDataAdapter("SELECT * FROM pie_data WHERE Pie_ID = ?", con))
{
    da.SelectCommand.Parameters.AddWithValue("Pie_ID", reference_id);
    da.Fill(tblPieData);
    var rowFields = tblPieData.AsEnumerable()
                              .Select(r => string.Join(",", r.ItemArray));
    finalString = string.Join("|", rowFields);
}

Answer 2

This line:

finalstring = finalstring.Remove(finalstring.Length -1, 1);

is going to remove the last instance of your pipe-delimiter, so if there is only one record (which there appears to be,) you shouldn't see one.

Unless I am missing something...

EDIT

Actually, if you are looking for two records, you are probably missing the second one because you start your loop with while(reader.Read()) and end it with reader.NextResult(); . These will both advance the reader, causing you to miss every other record.

EDIT 2

You are also overwriting finalstring on each iteration; you probably want to append to this (making it a StringBuilder would make the most sense for efficiency's sake, if you don't know how many records to expect.)

Answer 3

You are replacing the value of finalstring in every iteration of the loop. This will cause only the values for a single row to be returned:

finalstring = reader.GetString(9) + ",";

as well as removing the last character at the end of each iteration through the columns in the rows (the pipe, not the trailing comma as I'm expecting you want):

finalstring = finalstring.Remove(finalstring.Length -1, 1);

EDIT:

It also looks like you are skipping over every other record by both looping on reader.Read() as well as calling reader.NextResult()

Answer 4

Your looping structure with the reader appears to have some problems, not the least of which is the reset of finalAnswer within your loop and giving you only a single result combined with using both .Read() and .NextResult:

Suggested fixes...not tested, so all standard caveats apply :) :

Edited per Mark Averius' comment and OP confirmation of original intent:

using (OdbcDataReader reader = com.ExecuteReader()) {
  if (reader.HasRows())
  {
    string finalstring = "";
    while (reader.Read()) {
      finalstring = finalstring + reader.GetString(9) + ",";
      for (int i = 0; i <= 8; i++) {
        finalstring = finalstring + reader.GetValue(i).ToString() + ",";
      }
      finalstring = finalstring + "|";
    }
    if (finalstring != "") {
      finalstring = finalstring.Remove(finalstring.Length -1, 1);
      Response.Write(finalstring);
    }
  }

}