Find max value in column and icrease for 1...

Question

Why update complete column...not just active cell

 

SqlDataReader rdr;
                           SqlCommand cmd = new SqlCommand();


                           cmd.CommandText = "select max(brojprijavnice2) from dbo.prijava_radnika WHERE radnik = '" + readerresultTextbox.Text + "'";
                           cmd.Connection = con;
                           con.Open();
                           rdr = cmd.ExecuteReader();
                           int max = 0;
                           while (rdr.Read())
                           {
                               max = Convert.ToInt32(rdr[0].ToString());
                               Console.WriteLine(max);

                           }
                           con.Close();


                           String updateStaff = "UPDATE [dbo].[prijava_radnika] SET [vrijemeodjave] = @vrijemeodjave, brojprijavnice2 = " + (max + 1) + ", [status] = 'odjavljen' WHERE radnik = '" + readerresultTextbox.Text + "'";