How to generate auto id and show in textbox from button click event in .net c#

Hi,
You can use Random Class[^] to generate Random ID.
Try this:

private string RandomString(int size, bool lowerCase)
{
    StringBuilder builder = new StringBuilder();
    Random random = new Random();
    char ch ;
    for(int i=0; i<size;>    {
        ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65))) ;
        builder.Append(ch);
    }
    if(lowerCase)
    return builder.ToString().ToLower();
    return builder.ToString();
}

This function will return the Random ID.


--Amit

declare a global variable and increment it on each click

int id = 1;

//on button click
id++;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

namespace NewFurniture
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        OleDbConnection con = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|/Furniture.mdb");
        OleDbCommand cmd;
        OleDbDataAdapter da;
        OleDbDataReader dr;

        private void Button_Click(object sender, EventArgs e)
        {

try
            {
                textBox1.Enabled = false;

                int ctr, len;
                string codeval, code;
                DataRow drr;

                con.Open();
                da = new OleDbDataAdapter("select Customer_id from Customer",con);
                DataSet ds1 = new DataSet();
                da.Fill(ds1);

                DataTable dt;
                dt = ds1.Tables[0];
                len = dt.Rows.Count - 1;
                drr = dt.Rows[len];
                code = drr["Customer_id"].ToString();
                codeval = code.Substring(1, 3);

                ctr = Convert.ToInt32(codeval);

                if ((ctr >= 0) && (ctr < 9))
                {
                    ctr = ctr + 1;
                    textBox1.Text = "C00" + ctr;
                }
                else if ((ctr >= 9) && (ctr < 100))
                {
                    ctr = ctr + 1;
                    textBox1.Text = "C0" + ctr;
                }
                else if (ctr >= 99)
                {
                    ctr = ctr + 1;
                    textBox1.Text = "C" + ctr;
                }
                con.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error..." + ex.Message);
            }
}
}
}

hii,
If you want to create unique id,just use GUID .This Will Help you.
http://msdn.microsoft.com/en-us/library/system.guid.newguid.aspx[^]

if you want to generate unique auto generated no for column in database
just use identity property for sql server.