Calculte Value DataGridView

Question

I have a DataGridView like this :

ID	Depense	Recette	Balance
1	5	5	10
2	15	15	40

With id, Depense, Recette and Balance.

Balance is calculated by add Balance , Depence and Recette.

I have 3 button, AddProduct,UpdateProduct and DeleteProduct.

 * AddProduct : it will add a line into the DataGridView, but if the DataGridView is empty, (1st line )Balance = 0+5+5, and if isn't, (2nd line) Balance = 10+15+15=40,

 * UpdateProduct: I f I update a line, it will affect the other data, example, if I upadet the 1st line with Depense = 10, so the Balance in 1st will be 15 and the 2nd line will be 45.

* DeleteProduct : also the same idea with UpdateProduct's button but just remove the Balance from affected lines.

I code this part :

I modify the code and I call it when I click o button for test, the 1st click works perfect, but when I click again it add again sum, so I add another 'for' to calculate the balance for every row alone, but nothing happen, it stays the same problem

 

Decimal BalanceInput=0;
int IdTreInput;
private void UpdateBalance()
{
// calculate again somme of balance
for (int i = 0; i < DataGridViewTresorerie.Rows.Count; i++)
{
BalanceInput = Convert.ToDecimal(DataGridViewTresorerie.Rows[i].Cells[11].Value) + Convert.ToDecimal(DataGridViewTresorerie.Rows[i].Cells[12].Value);
IdTreInput = Convert.ToInt32(DataGridViewTresorerie.Rows[i].Cells[1].Value);
using (SqlConnection con = new SqlConnection(connstring))
{
using (SqlCommand cmd = new SqlCommand("Update Tresorerie set Balance= @Balance WHERE IdTre = @IdTre", con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@Balance", BalanceInput);
cmd.Parameters.AddWithValue("@IdTre", IdTreInput);
con.Open();
cmd.ExecuteNonQuery();
con.Close();
}
}
}

// update balance
for (int i = 0; i < DataGridViewTresorerie.Rows.Count; i++)
{
if (i == 0)

BalanceInput = Convert.ToDecimal(DataGridViewTresorerie.Rows[i].Cells[13].Value);
else
{
BalanceInput += Convert.ToDecimal(DataGridViewTresorerie.Rows[i].Cells[13].Value);
IdTreInput = Convert.ToInt32(DataGridViewTresorerie.Rows[i].Cells[1].Value);
using (SqlConnection con = new SqlConnection(connstring))
{
using (SqlCommand cmd = new SqlCommand("Update Tresorerie set Balance= @Balance WHERE IdTre = @IdTre", con))
{
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@Balance", BalanceInput);
cmd.Parameters.AddWithValue("@IdTre", IdTreInput);
con.Open();
cmd.ExecuteNonQuery();
con.Close();
}
}
//I call the new DataGridView to recalculate again after modify or add or delete the new data
BindGrid();
}
}
}