Dynamically change Windows Form DataGridView Header Text using C#

Hi simflex,

You can't change the header text dynamically as your no of column may vary. So instead of setting AutoGenerateColumns to false and bond DataGridView simply bind dt to DataGridView.

So that what ever the result set in your DataTable will be populated in the DataGridView.

Else please provide sample data of SummaryTable and the expected output you want to display in the DataGridView.

This year, it is 2019. Next year, 2020 will be added. We would like to be able to grab whatever the new column header is.

Based on your comment, I came up with this code.

First is sample data followed by the code I came up with

However, when I click to export data to excel, I get a message that object reference is not set to the instance of the object.

It is working good now.

I forgot to initialize the form with this: 

InitializeComponent();

TransactionID Amount AmountOwed  FullName Gender phone              EmailAddress             Address                               EventYear                       enelope_number Description        Reg_Fee  2019
8          120.00  0.00          John J Doe Male 443-393-2022       jdoe@att.net             33333 ankara dr                       2019-01-11 00:00:00.000         EV20199         Annual Dues       35.00    20.00
9          120.00 0.00           Carole Smith Male 443-111-2010     csmith@yahoo.com         342 Angel Str Atlanta, CA 20330       2019-01-12 00:00:00.000         EV5995          Annual Dues       35.00    60.00
10         120.00 70.00          James Ajukwara Male 678-222-1033    JAjukwara@yahoo.com     435 Williams Dr., Marietta, GA 30023  2019-01-13 00:00:00.000         EV4888          Annual Dues       35.00    50.00

namespace APOMembers
{

    public partial class Form2 : Form
    {
        //private DataGridView dataGridView1 = new DataGridView();
        private BindingSource bindingSource1 = new BindingSource();
        private SqlDataAdapter dataAdapter = new SqlDataAdapter();

        // Initialize the form.
        public Form2()
        {
            dataGridView1.Dock = DockStyle.Fill;

            //reloadButton.Text = "reload";
            //submitButton.Text = "submit";
            //reloadButton.Click += new System.EventHandler(reloadButton_Click);
            //submitButton.Click += new System.EventHandler(submitButton_Click);

            FlowLayoutPanel panel = new FlowLayoutPanel();
            panel.Dock = DockStyle.Top;
            panel.AutoSize = true;
            //panel.Controls.AddRange(new Control[] { reloadButton, submitButton });

            this.Controls.AddRange(new Control[] { dataGridView1, panel });
            this.Load += new System.EventHandler(Form2_Load);

        }

        private void Form2_Load(object sender, System.EventArgs e)
        {
            // Bind the DataGridView to the BindingSource
            // and load the data from the database.
            dataGridView1.DataSource = bindingSource1;
            GetData("select * from SummaryTable");
        }

        private void reloadButton_Click(object sender, System.EventArgs e)
        {
            // Reload the data from the database.
            GetData(dataAdapter.SelectCommand.CommandText);
        }

        private void submitButton_Click(object sender, System.EventArgs e)
        {
            // Update the database with the user's changes.
            dataAdapter.Update((DataTable)bindingSource1.DataSource);
        }

        private void GetData(string selectCommand)
        {
            try
            {
                // Specify a connection string. Replace the given value with a 
                // valid connection string for a Northwind SQL Server sample
                // database accessible to your system.
                String connectionString = ConfigurationManager.ConnectionStrings["Members"].ConnectionString;

                // Create a new data adapter based on the specified query.
                dataAdapter = new SqlDataAdapter(selectCommand, connectionString);

                // Create a command builder to generate SQL update, insert, and
                // delete commands based on selectCommand. These are used to
                // update the database.
                SqlCommandBuilder commandBuilder = new SqlCommandBuilder(dataAdapter);

                // Populate a new data table and bind it to the BindingSource.
                DataTable table = new DataTable();
                table.Locale = System.Globalization.CultureInfo.InvariantCulture;
                dataAdapter.Fill(table);
                bindingSource1.DataSource = table;

                // Resize the DataGridView columns to fit the newly loaded content.
                dataGridView1.AutoResizeColumns(
                    DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader);
            }
            catch (SqlException)
            {
                MessageBox.Show("There is an issue with connection string.");
            }
        }

        private void btnExportExcel_Click(object sender, EventArgs e)
        {
            //create datetime placeholder
            DateTime curdate = DateTime.Now;

            //Creating DataTable
            DataTable dt = new DataTable();

            //Adding the Columns
            foreach (DataGridViewColumn column in dataGridView1.Columns)
            {
                dt.Columns.Add(column.HeaderText, column.ValueType);
            }

            //Adding the Rows
            foreach (DataGridViewRow row in dataGridView1.Rows)
            {
                dt.Rows.Add();
                foreach (DataGridViewCell cell in row.Cells)
                {
                    dt.Rows[dt.Rows.Count - 1][cell.ColumnIndex] = cell.Value.ToString();
                }
            }

            //Exporting to Excel
            string folderPath = "C:\\Excel\\";
            if (!Directory.Exists(folderPath))
            {
                Directory.CreateDirectory(folderPath);
            }
            using (XLWorkbook wb = new XLWorkbook())
            {
                wb.Worksheets.Add(dt, "Summary");
                wb.SaveAs(folderPath + curdate + "APOReport.xlsx");
                MessageBox.Show("Data Successfully exported to Excel file"
            }
        }
    }
}

Thank you very much for the great feedback