How To Change Datagridview ComboboxCell and TextBoxCell's Text When Datagridview ComboBoxCell Selected Index Changes

Hi, i'm facing datagridview problem and also i google it but didn't found any working solution. Please help me in solving my problem.

i have DataGridView with below Column:
1st Column is "ComboBoxCell" Hearder "CategoryCode"
2nd Column is "ComboBoxCell" Hearder "ProductCode"
3rd Column is "TextBoxCell" Hearder "ProductName"

also i have a database(named:SSProducts) with two tables
1st table is Category(Columns: CategoryCode, CategoryName)
2nd table is Product(Columns: CategoryCode, ProductCode, ProductName)

when DataGridView form is open then the 1st column of DataGridView is fill with the value of DataBase Category table. for that i write the below code and the code is working correctly.

private void Category_Product_Load(object sender, EventArgs e)
        {
            fillcategorycombo();
        }

        private void fillcategorycombo()
        {
            try
            {
                //DataGridView 1st Column Name
                ENPB_categorycode.Items.Clear();
                using (SQLiteConnection conn = new SQLiteConnection(StockCategoriesComboFill.Conn()))
                {
                    string CommandText = "SELECT CategoryCode FROM Category ORDER BY CategoryCode";
                    using (SQLiteCommand cmd = new SQLiteCommand(CommandText, conn))
                    {
                        conn.Open();
                        cmd.ExecuteNonQuery();
                        DataTable dt = new DataTable();
                        SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
                        da.Fill(dt);
                        foreach (DataRow dr in dt.Rows)
                        {
                            ENPB_categorycode.Items.Add(dr["CategoryCode"].ToString());
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                XtraMessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

when form is load the 1st column of DataGridView is filled with database value correctly. My problem is that:

when the user select the CategoryCode from 1st DataGridView ComboBoxCell then the 2nd DataGridView ComboBoxCell filled with database 2nd table(Product) column(ProductCode).

i write below code to fill 2nd DataGridView ComboboxCell with database but i didn't know where i use it.

private void fillproductcombo()
        {
            try
            {
                ENPB_detail.Items.Clear();
                if (ENPB_categorycode.Selected)
                {
                    using (SQLiteConnection conn = new SQLiteConnection(StockProductsComboFill.Conn()))
                    {
                        string CommandText = "SELECT * FROM Product WHERE [CategoryCode]=@id";
                        using (SQLiteCommand cmd = new SQLiteCommand(CommandText, conn))
                        {
                            cmd.Parameters.AddWithValue("@id", ENPB_categorycode.Selected.ToString());
                            conn.Open();
                            cmd.ExecuteNonQuery();
                            DataTable dt = new DataTable();
                            SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
                            da.Fill(dt);
                            foreach (DataRow dr in dt.Rows)
                            {
                                ENPB_detail.Items.Add(dr["ProductName"].ToString());
                            }
                        }
                    }
                }
                else
                {
                    XtraMessageBox.Show("Please Select the Category Code From the List", "Category isn't Selected", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception ex)
            {
                XtraMessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

Tell me where i use this code to fill my second DataGridView comboboxcell. In combobox there is a event called SelectedChangeIndex, but DataGridView comboboxcell have no such event.

Help me how can i do that, also i want to that when user select 2nd comboboxcell value then show the name of that value in 3rd column of DataGridView.

waiting for help...