updating data after printing it in DB

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C#

WinForms

i want to update data after printing it .
for example if admin enter :

previous account=30
added account=40
then:
total account=70

the result will be stored in DB(total account=70) and also will be printed in gridview

but actually after printing ,i want to update previous account=70
how can i do this

SqlConnection con = new SqlConnection(@"");
           SqlCommand command = new SqlCommand();
           command.Connection = con;
           command.CommandText = "update customer set   jj=@a where jj=@d";
           command.Parameters.AddWithValue("@d",name);
           command.Parameters.AddWithValue("@a",total);
           try
           {
               con.Open();
               int i = command.ExecuteNonQuery();
               if (i > 0)
                   con.Close();

           }
           catch(Exception ex)
           {
               throw(ex);
           }
       }