alphanumeric number inserting into sql using csharp

Question

sir i want to generate alphanumeric number to my label in c# windows form 

this is my code

 

public class DBcodes

{

public string Sales_Invoice {get; set;}

public string Customer_Name {get; set;}

public string Mobile_No {get; set;}

public string Address {get; set;}

public string Item_Name {get; set;}

public string Item_Code {get; set;}

public string Dept {get; set;}

public string Date {get; set;}

public int Qty {get; set;}

public int Rate {get; set;}

public int Vat_tax {get; set;}

public int Amount {get; set;}

public int Payment_Type {get; set;}

public int Purchase_ID { get; set; }

string myConnection =

 

public void retriveData()

{

string selQuery="select sales_invoice from sales";

try

{

SqlConnection conn= new SqlConnection (myConnection);

conn.Open();

SqlCommand cmd = new SqlCommand (selQuery, conn);

Sales_Invoice=(string)cmd.ExecuteScalar();

conn.Close();

}

catch

{

Sales_Invoice=name/sales/1000;

 

please help me