我的数据库事务是否正确？

Question

My code is very slow I takes at least 10 sec to run this metod. I have a arrayList with ingredients that I need to go through. for each of these ingredients I need to change the quantity in the database. All the items are in rawmaterials table. Is my code correct with respect to transaction ? Where should I do commit? In my code I am going to lock the whole table while I am updating the ingredients for one cookie

public void ProducePallet(string prodName, DateTime date)
{
    MySqlCommand cmd = new MySqlCommand();
    cmd.Connection = conn;
    cmd.CommandText =
        "INSERT INTO pallets(prodName,prodDate,blocked,orderID) VALUES(@name,@date, false, null)";
    cmd.Prepare();
    cmd.Parameters.AddWithValue("@name", prodName);
    cmd.Parameters.AddWithValue("@date", date);
    cmd.ExecuteNonQuery();

    cmd = new MySqlCommand();
    cmd.Connection = conn;
    cmd.CommandText =
        "Select mName, quantity from recipes natural join ingredients where prodName=@pName";
    cmd.Prepare();
    cmd.Parameters.AddWithValue("@pName", prodName);
    cmd.ExecuteNonQuery();

    ArrayList ingredients = new ArrayList();
    string[] ingredientsPair;
    MySqlDataReader rdr = cmd.ExecuteReader();
    while (rdr.Read())
    {
        ingredientsPair = new string[2];
        ingredientsPair[0] = rdr.GetString(0); //Ingredient name
        ingredientsPair[1] = rdr.GetString(1); //Quantity
        ingredients.Add(ingredientsPair);

    }
    rdr.Close();
    MySqlTransaction tr = conn.BeginTransaction();
    foreach (string[] i in ingredients)
    {

        cmd = new MySqlCommand();
        cmd.Connection = conn;
        cmd.CommandText = "Select quantityLeft from rawmaterials where mName=@mName for update";
        cmd.Prepare();
        cmd.Parameters.AddWithValue("@mName", i[0]);
        rdr = cmd.ExecuteReader();
        int mQuantity = 0;
        while (rdr.Read())
        {
            mQuantity = rdr.GetInt32(0);
        }
        rdr.Close();
        mQuantity -= Int32.Parse(i[1]) * 36 * 10 * 15 / 100;
        //cmd = new MySqlCommand();
        //cmd.Connection = conn;
        cmd.CommandText = "Update rawmaterials Set quantityLeft = @newQL where mName=@mName";
        cmd.Prepare();
        cmd.Parameters.AddWithValue("@newQL", mQuantity);
        // cmd.Parameters.AddWithValue("@mName", i[0]);
        cmd.ExecuteNonQuery();


    }

    try
    {

        tr.Commit();
    }
    catch (Exception e)
    {
        try
        {
            tr.Rollback();
        }
        catch (Exception e2)
        {
            Debug.WriteLine(e2.ToString());
        }
        return;
    }
}

Raw material Table

 mName           quantityLeft
Bread crumbs    8959500
Butter  7782300
Chocolate   8946000
Chopped almonds 8623350
Cinnamon    8986500
Egg whites  8886600
Eggs    8867700
Fine-ground nuts    8757000
Flour   7774200
Ground, roasted nuts    8797500
Icing sugar 8780760
Marzipan    8716500
Potato starch   8990550
Roasted, chopped nuts   8829900
Sodium bicarbonate  8998920
Sugar   8446500
Vanilla 8999460
Vanilla sugar   8996220
Wheat flour 8990550

Answer 1

Add "SET AUTOCOMMIT=0"; and "START TRANSACTION;" before starting the transaction.

Hope this will help you out.