how can i auto genrete a number in vb.net?

i want to genrete a auto number in my project....

i used vb .net 2008 and SQl server 2005 as backend ??

i want to create a serial no that is like abc/2010/01..In this..

1. the abc is same in all the serial no.
2. the 2010 is used from the running Year.(using date for year)
3. the 01 is a actual serial no that can be auto genrete...

But how can i do this ....?? and How can i find max number from my serial no.....??? how can i maintain it if i delete it then all after delete serial no will place it's place..(there is no break in serial n开发者_如何学JAVAo on delete) ?????? Please help me.....

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here is the code snippet for generate newid i have taken a simple label and textbox label will auto generate newid and textbox will insert a new record in database take a label and textbox in your design page

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 
{
    public  static int temp;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            newcode();
        }

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
       SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS;Initial Catalog=practice;Integrated Security=True;");

       con.Open();
        SqlCommand cmd = new SqlCommand("Insert into frmlogin(id,username) values ("+ temp+",'"+TextBox1.Text+"')", con);
        cmd.CommandType = CommandType.Text;
       cmd.Parameters.AddWithValue("username", TextBox1.Text);

        cmd.ExecuteNonQuery();
        con.Close();
        TextBox1.Text = "";
        Label1.Text = "";
        newcode();

    }
    public void newcode()
    {
        SqlConnection con1 = new SqlConnection("Data Source=.\\SQLEXPRESS;Initial Catalog=practice;Integrated Security=True;");
        con1.Open();
        SqlCommand cmd2 = new SqlCommand("Select Max(id) as empid from frmlogin", con1);
        cmd2.CommandType = CommandType.Text;
        SqlDataReader r = cmd2.ExecuteReader();
        r.Read();

        if (r["empid"].ToString() != "")
        {
            temp = int.Parse(r["empid"].ToString()) + 1;
        }
        else
        {
            temp = 1;

        }

        Label1.Text= temp.ToString();
        r.Close();
        con1.Close();
    }



}

The main thing is that you should maintain your incremented number somewhere, In my case i have used textbox and label.

But I did rather recommend you to go for GUID or Random Number.

for GUID :

System.Guid.NewGuid().ToString(); 

Have Look here as well

for Random Number Generation

::: Program that uses Random type [C#] :::

using System;

class Program
{
    static void Main()
    {
        Random random = new Random();
        Console.WriteLine(random.Next());
        Console.WriteLine(random.Next());
    }
}

::: Output of the program :::

1592498984
1526415661

Try this

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You could store the serial numbers in a database table where the third component of the number is the primary key of the table as an identity field. Any time you create a new serial number, you'd insert the current year and the static text into the table. An easy way to do this would be to wrap that logic in a stored procedure which takes no arguments, internally inserts the current year and the text, and returns the entire serial number as a single scalar value.

Something like:

INSERT INTO SerialNumbers (Year, Name) VALUES (year(getdate()), 'abc')

and:

SELECT Name + '/' + CAST(Year AS nvarchar) + '/' + CAST(ID AS nvarchar) FROM SerialNumbers WHERE ID = SCOPE_IDENTITY()