C#: How do i select columns of data from csv, stored in an array/datatable?

Question

I've successfully loaded a .csv file into an array which i set into a dataset/datagridview control for viewing. The issue I have been having is trying to think of a way to:

Select columns of imported data (in terms of UI)
Store the fresh selection of information for review

The current code i have allows the user to browse for the file on their system and stores the data in an array and sets it into a datatable.

    private void btnBrowse_Click(object sender, EventArgs e)
    {
        #region Local Variables
        int nRows = 0;      //Row Counter
        int icol = 0;       //Index value for Columns -> fArray
        int irow = 0;       //Index value for Row -> fArray
        string Line;        //Temp string value for storing lines
        #endregion

        #region File Open Parameters
        //file open parameters
        OpenFileDialog fopen = new OpenFileDialog();
        fopen.Title = "Choose file...";
        fopen.Filter = "Comma Seperated Values|*.csv";
        fopen.InitialDirectory = @"C:\";
        #endregion

        if (fopen.ShowDialog() == DialogResult.OK) //Show file open dialog and check if ok has been pressed
        {
            #region progress bar initialisation
            //initialize progress bar
            pb.Location = new Point(60, 209);
            pb.Width = 516;
            pb.Height = 23;
            pb.Style = ProgressBarStyle.Continuous;
            pnlStep1.Controls.Add(pb);
            #endregion

            try
            {
                StreamReader fReader = new StreamReader(fopen.FileName);

                #region Array Index Counters
                //Count Columns for fArray index
                string count = fReader.ReadLine();
                string[] tmpCount = count.Split(',');
                fReader.Close();

                //Count Rows for fArray index
                fReader = new StreamReader(fopen.FileName); //begin reading from line 1
                while ((fReader.ReadLine()) != null)
                {
                    nRows++;
                }

                fArray = new string[nRows, tmpCount.Length];
                fReader.Close();
                //End count
                #endregion

                #region Load File Contents
                fReader = new StreamReader(fopen.FileName); //begin reading from line 1
                DataSet ds = new DataSet();
                dt = ds.Tables.Add("ImportData");

                while ((Line = fReader.ReadLine()) != null)
                {
                    string[] row = Line.Split(',');
                    foreach (string column in row)
                    {
                        fArray[irow, icol] = column;
                        icol++;
                    }
                    icol = 0;
                    recordCountLabel.Text = irow.ToString(); //NEEDS LOOKING AT
                    pb.Value = (irow * 100) / fArray.GetLength(0);
                    irow++;
                }
                pb.Value = 100;
                fReader.Close();
                #endregion

                #region Add data to dgImport
                for (int i = 0; i < fArray.GetLength(1); i++) //Add Columns to empty DataGridView
                {
                    dt.Columns.Add("Field " + i.ToString());
                }

                for (int i = 0; i < 3; i++) //Insert data into DataGridView (use fArray.GetLength(0) for entire database or use 5 for sample data)
                {
                    DataRow row = dt.NewRow();
                    for (int j = 0; j < fArray.GetLength(1); j++)
                    {
                        row[j] = fArray[i, j].Trim();
                    }
                    dt.Rows.Add(row);
                    dgImport.DataSource = dt;
                }

                btnNext2.Enabled = true;
                #endregion

            }
            catch (Exception ex)
            {
                MessageBox.Show("Error: Could not read file from disk.\r\nOriginal error: " + ex.Message);
            }
        }   
    }

Any help would be greatly appreciated :).

EDIT: Sorry to be a pain again i forgot to mention, i show a few sample rows of data in a datagridview control and was looking at providing a list of dynamically created checkboxes allowing the user to tick what columns he/she wants to select (essentially copying only the data that is selected).

Or use linq; much faster than oledb

user1513190
– user1513190

2012-07-09 21:49:30 +00:00
Commented Jul 9, 2012 at 21:49 — user1513190
– user1513190, Commented Jul 9, 2012 at 21:49

KV Prajapati · Accepted Answer · 2012-07-03 10:36:07Z

2

You need to read csv using OleDb Provider. That way you may specify the set of columns you want to include in SELECT statement.

EDIT:

 string location=@"c:\folder\";
 string cnstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + location + ";Extended Properties=\"text;HDR=No;FMT=Delimited\";";
 string sql = "select F2,F1 from test.csv";

 using (OleDbDataAdapter adp = new OleDbDataAdapter(sql, cnstr))
  {
    DataTable dt = new DataTable();
    adp.Fill(dt);

    foreach (DataRow row in dt.Rows)
    {
       Console.WriteLine(row[0] + " " + row[1]);
    }
  }

edited Jul 3, 2012 at 10:36

answered Jul 3, 2012 at 10:24

KV Prajapati

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2 Comments

Tayvius Over a year ago

A part of the requirements is that a customer might not always have column headers defined which made me go against that idea a bit.

KV Prajapati Over a year ago

You may specify the column alias F1 (for first column),F2 to select the columns.

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