Как обновить DataGridView

private void button1_Click(object sender, EventArgs e)
        {
            List<CurrencyRate> list = GetExchangeRates();
            sqlConnection = new SqlConnection(ConnectionString);
            sqlConnection.Open();
            SqlCommand command = null;
            for (int i = 0; i < list.Count; i++)
            {
                command = new SqlCommand("Insert into [dbo].[Currency_DUMP] (CurrencyStringCode,CurrencyName,ExchangeRate,CurrencyCode,CurrencyNominal,CurrencyDate) Values(@CurrencyStringCode,@CurrencyName,@ExchangeRate,@CurrencyCode,@CurrencyNominal,@CurrencyDate)", sqlConnection);
                command.Parameters.AddWithValue("CurrencyStringCode", list[i].CurrencyStringCode);
                command.Parameters.AddWithValue("CurrencyName", list[i].CurrencyName);
                command.Parameters.AddWithValue("ExchangeRate", list[i].ExchangeRate);
                command.Parameters.AddWithValue("CurrencyCode", list[i].CurrencyCode);
                command.Parameters.AddWithValue("CurrencyNominal", list[i].CurrencyNominal);
                command.Parameters.AddWithValue("CurrencyDate", list[i].CurrencyDate);
                command.ExecuteNonQuery();
            }
 
            string mergeSql =   "Merge [dbo].[Currency] as Target " +
                                "Using (Select distinct    Source.CurrencyStringCode,Source.CurrencyName,Source.ExchangeRate,Source.CurrencyCode,Source.CurrencyNominal,Source.CurrencyDate from [dbo].[Currency_DUMP]  as Source) as Source " +
                                "on " +
                                "Target.CurrencyDate = Source.CurrencyDate and Target.CurrencyName = Source.CurrencyName and Target.CurrencyCode = Source.CurrencyCode " +
                                "When not matched then INSERT (CurrencyStringCode,CurrencyName,ExchangeRate,CurrencyCode,CurrencyNominal,CurrencyDate) Values (Source.CurrencyStringCode,Source.CurrencyName,Source.ExchangeRate,Source.CurrencyCode,Source.CurrencyNominal,Source.CurrencyDate)" +
                                ";";
 
            command = new SqlCommand(mergeSql, sqlConnection);
            command.ExecuteNonQuery();
 
            sqlConnection.Close();
 
 
        }