c# - Create column to calculate moving average

Question

I created table using VS2012, C#. I want to add column that calculates moving averages for Cclose column.

Below is my code to create the table

  string cmdText = "CREATE TABLE [" + TblName + "]"
                 + "(Tticker char(6),"
                 + "Pper char(1),"
                 + "Ddate date,"
                 + "Ttime TIME,"
                 + "Oopen float(6),"
                 + "Hhigh float(6),"
                 + "Llow float(6),"
                 + "Cclose float(6),"
                 + "Vvol char(15))";
  SqlCommand cmd = new SqlCommand(cmdText, con);
  cmd.ExecuteNonQuery();

I want to add column to calculate MV for last three Cclose values. Appreciate your support..thanks.