C#

DataGridView newdtgv = dataGridView1;
newdtgv.Columns["customercode"].Visible = false;
printer.PrintPreviewDataGridView(dataGridView1);

using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        private SqlConnection conn;
        private string connStr;
        SqlDataAdapter da;
        DataSet ds;
        bool b;

        public Form1()
        {
            InitializeComponent();
            connStr = "Data Source=.\\SQLEXPRESS;AttachDbFilename=" + Application.StartupPath + "\\dbOne.mdf" + ";Integrated Security=True;Connect Timeout=30;User Instance=True";
            conn = new SqlConnection(connStr);
            conn.Open();
            string selectStr = "select * from people";
            da = new SqlDataAdapter(selectStr, conn);
            ds=new DataSet();
            da.Fill(ds,"people");

            da.InsertCommand = new SqlCommand("insert into people(name, age) values (@name, @age)", conn);
            da.InsertCommand.Parameters.Add("@name",SqlDbType.VarChar,50,"name");
            da.InsertCommand.Parameters.Add("@age",SqlDbType.Int,5,"age");

            da.UpdateCommand = new SqlCommand("update people set name=@name, age=@age where id=@id",conn);
            da.UpdateCommand.Parameters.Add("@name",SqlDbType.VarChar,50,"name");
            da.UpdateCommand.Parameters.Add("@age",SqlDbType.Int,5,"age");
            da.UpdateCommand.Parameters.Add("@id",SqlDbType.Int,5,"id");

            da.DeleteCommand = new SqlCommand("delete from people where id=@id",conn);
            da.DeleteCommand.Parameters.Add("@id",SqlDbType.Int,5,"id");

            dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
            dataGridView1.DataSource = ds.Tables["people"];
            txtId.DataBindings.Add("Text",ds.Tables["people"],"id");
            txtName.DataBindings.Add("Text", ds.Tables["people"], "name");
            txtAge.DataBindings.Add("Text", ds.Tables["people"], "age");

            txtId.Enabled = false; txtName.Enabled = false; txtAge.Enabled = false; 
            btnSave.Enabled = false; btnCancel.Enabled = false;
            conn.Close();
        }

        private void btnChange_Click(object sender, EventArgs e)
        {
            b = false;
            txtName.Enabled = true; txtAge.Enabled = true;
            btnNew.Enabled = false; btnDelete.Enabled = false; btnSave.Enabled = true; btnCancel.Enabled = true;
        }

        private void btnSave_Click(object sender, EventArgs e)
        {            
            if (b) // insert new line
            {
                DataRow newLine = ds.Tables["people"].NewRow();
                newLine["name"] = txtName.Text;
                newLine["age"] = txtAge.Text;
                ds.Tables["people"].Rows.Add(newLine);
            }
            da.Update(ds,"people");
        }

        private void btnNew_Click(object sender, EventArgs e)
        {
            b = true;
            int i = ds.Tables["people"].Rows.Count;
            dataGridView1.Rows[i].Selected = true;

            txtId.Text = ""; txtName.Text = ""; txtAge.Text = "";
            txtName.Enabled = true; txtAge.Enabled = true;
            btnSave.Enabled = true; btnCancel.Enabled = true;
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            int i = int.Parse(dataGridView1.CurrentRow.Index.ToString());
            ds.Tables["people"].Rows[i].Delete();
            da.Update(ds,"people");
        }


    }
}

private void evtOpenFile_Click(object sender, EventArgs e)
        {
            openFileDialog1.Multiselect = true;
            

            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {

                foreach (String file in openFileDialog1.FileNames)
                {

                    evtNewDocument_Click(sender, e);
                    
                    
                    RichTextBox richTextBox1 = new RichTextBox();

                    richTextBox1 = tabControl1.SelectedTab.Controls[0] as RichTextBox;

                    richTextBox1.LoadFile(openFileDialog1.FileName,RichTextBoxStreamType.PlainText);
                    saveFileDialog1.FileName = openFileDialog1.FileName;

                    FileInfo fi = new FileInfo(openFileDialog1.FileName);
                    string pot = fi.Name;

                    tabControl1.SelectedTab.Text = pot;

                    pot = "";
                }
                

            }
        }