GUIDE.txt - main - DataTimeModule/DateTime

GUIDE.txt
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27 май 2026, 01:50
27 май 2026, 01:50f282598
Модуль 2. Авторизация и список товаров
1. Подготовка проекта
Создать WinForms проект.

NuGet:

Microsoft.Data.SqlClient
Добавить папку:

Images
Положить:

Icon.png
picture.png
1.jpg ... 10.jpg
В .csproj можно добавить:

<ItemGroup>
  <Content Include="Images\*.*">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </Content>
</ItemGroup>
2. Db.cs
Создать файл Db.cs.

using Microsoft.Data.SqlClient;
using System.Data;

namespace demo1;

internal static class Db
{
    private const string ConnectionString =
        "Data Source=localhost;Initial Catalog=demo1;Integrated Security=True;TrustServerCertificate=True";

    public static SqlConnection OpenConnection()
    {
        var connection = new SqlConnection(ConnectionString);
        connection.Open();
        return connection;
    }

    public static void LoadComboBox(ComboBox comboBox, string sql, string display, string value)
    {
        using var connection = OpenConnection();
        var table = new DataTable();
        new SqlDataAdapter(sql, connection).Fill(table);
        comboBox.DataSource = table;
        comboBox.DisplayMember = display;
        comboBox.ValueMember = value;
    }

    public static Image GetImage(string? fileName)
    {
        string path = Path.Combine(AppContext.BaseDirectory, "Images", fileName?.Trim() ?? "");

        if (!File.Exists(path))
        {
            path = Path.Combine(AppContext.BaseDirectory, "Images", "picture.png");
        }

        using var image = Image.FromFile(path);
        return new Bitmap(image);
    }
}
3. Form1
Компоненты:

PictureBox logoPictureBox
TextBox loginTextBox
TextBox passwordTextBox
Button enterButton
Button guestButton
Свойства:

passwordTextBox.PasswordChar = *
logoPictureBox.SizeMode = Zoom
4. Form1.cs
namespace demo1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            LoadLogo();
        }

        private void LoadLogo()
        {
            string path = Path.Combine(AppContext.BaseDirectory, "Images", "Icon.png");
            if (File.Exists(path))
            {
                logoPictureBox.Image = Image.FromFile(path);
            }
        }

        private void enterButton_Click(object sender, EventArgs e)
        {
            string login = loginTextBox.Text.Trim();
            string password = passwordTextBox.Text.Trim();

            if (login == "" || password == "")
            {
                MessageBox.Show("Введите логин и пароль.", "Ошибка");
                return;
            }

            using var connection = Db.OpenConnection();

            string sql = """
                SELECT TOP 1
                    u.Surname + N' ' + u.Name + N' ' + ISNULL(u.Patronymic, N'') AS FullName,
                    r.Title AS RoleTitle
                FROM Users u
                JOIN Roles r ON u.RoleId = r.RoleId
                WHERE u.Login = @login AND u.Password = @password
                """;

            using var command = new Microsoft.Data.SqlClient.SqlCommand(sql, connection);
            command.Parameters.AddWithValue("@login", login);
            command.Parameters.AddWithValue("@password", password);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                MessageBox.Show("Неверный логин или пароль.", "Ошибка");
                return;
            }

            OpenProducts(reader["FullName"].ToString()!, reader["RoleTitle"].ToString()!);
        }

        private void guestButton_Click(object sender, EventArgs e)
        {
            OpenProducts("Гость", "Гость");
        }

        private void OpenProducts(string fullName, string role)
        {
            Hide();
            var form = new ProductForm(fullName, role);
            form.FormClosed += (_, _) => Show();
            form.Show();
        }
    }
}
Модуль 2-3. Карточка товара
1. ProductCard
Создать:

UserControl ProductCard
Компоненты:

PictureBox photoBox
Label infoLabel
Label priceLabel
Label discountPriceLabel
Label discountLabel
Button editButton
Button deleteButton
Свойства:

photoBox.SizeMode = Zoom
2. ProductCard.cs
namespace demo1
{
    public partial class ProductCard : UserControl
    {
        public event Action<string>? EditProduct;
        public event Action<string>? DeleteProduct;

        private string article = "";

        public ProductCard()
        {
            InitializeComponent();
        }

        public void SetProduct(string article, Image photo, string title, string category,
            string description, string manufacturer, string provider, decimal price,
            int discount, int stock, string unit, bool isAdmin)
        {
            this.article = article;
            photoBox.Image = photo;
            editButton.Visible = isAdmin;
            deleteButton.Visible = isAdmin;

            infoLabel.Text =
                $"{category} | {title}\n" +
                $"Описание товара: {description}\n" +
                $"Производитель: {manufacturer}\n" +
                $"Поставщик: {provider}\n" +
                $"Единица измерения: {unit}\n" +
                $"Количество на складе: {stock}";

            priceLabel.Text = $"Цена: {price:0.00}";
            discountLabel.Text = $"Скидка\n{discount}%";

            if (discount > 0)
            {
                decimal newPrice = price * (100 - discount) / 100;
                priceLabel.ForeColor = Color.Red;
                priceLabel.Font = new Font(Font, FontStyle.Strikeout);
                discountPriceLabel.Text = $"{newPrice:0.00}";
            }

            if (stock == 0)
            {
                BackColor = Color.LightBlue;
            }
            else if (discount > 15)
            {
                BackColor = Color.SeaGreen;
            }
        }

        private void editButton_Click(object sender, EventArgs e)
        {
            EditProduct?.Invoke(article);
        }

        private void deleteButton_Click(object sender, EventArgs e)
        {
            DeleteProduct?.Invoke(article);
        }
    }
}
Модуль 2-3. Список товаров
1. ProductForm
Компоненты:

Label userLabel
Button exitButton
TextBox searchTextBox
ComboBox providerComboBox
ComboBox sortComboBox
Button addButton
Button ordersButton
FlowLayoutPanel productsPanel
Свойства:

productsPanel.AutoScroll = True
productsPanel.FlowDirection = TopDown
productsPanel.WrapContents = False

providerComboBox.DropDownStyle = DropDownList
sortComboBox.DropDownStyle = DropDownList
2. ProductForm.cs
using Microsoft.Data.SqlClient;

namespace demo1
{
    public partial class ProductForm : Form
    {
        private readonly string role;
        private ProductEditForm? editForm;

        public ProductForm(string fullName, string role)
        {
            InitializeComponent();
            this.role = role;
            userLabel.Text = $"{role}: {fullName}";
        }

        private bool CanManageProducts => role == "Администратор";
        private bool CanFilterProducts => role == "Администратор" || role == "Менеджер";

        private void ProductForm_Load(object sender, EventArgs e)
        {
            searchTextBox.Visible = CanFilterProducts;
            providerComboBox.Visible = CanFilterProducts;
            sortComboBox.Visible = CanFilterProducts;
            addButton.Visible = CanManageProducts;
            ordersButton.Visible = CanFilterProducts;

            sortComboBox.Items.AddRange(new[] { "Без сортировки", "Остаток ↑", "Остаток ↓" });
            sortComboBox.SelectedIndex = 0;

            LoadProviders();
            LoadProducts();
        }

        private void LoadProviders()
        {
            providerComboBox.Items.Clear();
            providerComboBox.Items.Add("Все поставщики");

            using var connection = Db.OpenConnection();
            using var command = new SqlCommand("SELECT Title FROM Providers ORDER BY Title", connection);
            using var reader = command.ExecuteReader();

            while (reader.Read())
            {
                providerComboBox.Items.Add(reader["Title"].ToString()!.Trim());
            }

            providerComboBox.SelectedIndex = 0;
        }

        private void LoadProducts()
        {
            productsPanel.Controls.Clear();

            using var connection = Db.OpenConnection();

            string sql = """
                SELECT p.Article, p.Title, c.Title AS Category, p.Description,
                       m.Title AS Manufacturer, pr.Title AS Provider,
                       p.Price, p.Discount, p.StockQuantity, u.Title AS Unit, p.PhotoPath
                FROM Products p
                JOIN ProductCategories c ON p.ProductCategoryId = c.ProductCategoryId
                JOIN Manufacturers m ON p.ManufacturerId = m.ManufacturerId
                JOIN Providers pr ON p.ProviderId = pr.ProviderId
                JOIN Units u ON p.UnitId = u.UnitId
                WHERE (@provider = N'' OR pr.Title = @provider)
                  AND (@search = N'' OR
                       p.Title LIKE @like OR p.Description LIKE @like OR
                       c.Title LIKE @like OR m.Title LIKE @like OR pr.Title LIKE @like OR u.Title LIKE @like)
                ORDER BY
                    CASE WHEN @sort = 1 THEN p.StockQuantity END,
                    CASE WHEN @sort = 2 THEN p.StockQuantity END DESC,
                    p.Title
                """;

            using var command = new SqlCommand(sql, connection);
            string provider = providerComboBox.SelectedIndex > 0 ? providerComboBox.Text : "";
            string search = searchTextBox.Text.Trim();
            int sort = sortComboBox.SelectedIndex;

            command.Parameters.AddWithValue("@provider", provider);
            command.Parameters.AddWithValue("@search", search);
            command.Parameters.AddWithValue("@like", $"%{search}%");
            command.Parameters.AddWithValue("@sort", sort);

            using var reader = command.ExecuteReader();

            while (reader.Read())
            {
                var card = new ProductCard();

                card.SetProduct(
                    reader["Article"].ToString()!,
                    Db.GetImage(reader["PhotoPath"].ToString()),
                    reader["Title"].ToString()!,
                    reader["Category"].ToString()!,
                    reader["Description"].ToString()!,
                    reader["Manufacturer"].ToString()!,
                    reader["Provider"].ToString()!,
                    Convert.ToDecimal(reader["Price"]),
                    Convert.ToInt32(reader["Discount"]),
                    Convert.ToInt32(reader["StockQuantity"]),
                    reader["Unit"].ToString()!,
                    CanManageProducts);

                card.EditProduct += OpenEditForm;
                card.DeleteProduct += DeleteProduct;
                productsPanel.Controls.Add(card);
            }
        }

        private void filter_Changed(object sender, EventArgs e)
        {
            if (CanFilterProducts && sortComboBox.SelectedIndex >= 0 && providerComboBox.SelectedIndex >= 0)
            {
                LoadProducts();
            }
        }

        private void addButton_Click(object sender, EventArgs e)
        {
            OpenEditForm("");
        }

        private void ordersButton_Click(object sender, EventArgs e)
        {
            new OrdersForm(CanManageProducts).ShowDialog();
        }

        private void OpenEditForm(string article)
        {
            if (editForm != null)
            {
                editForm.Activate();
                return;
            }

            editForm = new ProductEditForm(article);
            editForm.FormClosed += (_, _) =>
            {
                editForm = null;
                LoadProducts();
            };
            editForm.Show();
        }

        private void DeleteProduct(string article)
        {
            if (MessageBox.Show("Удалить товар?", "Подтверждение", MessageBoxButtons.YesNo) != DialogResult.Yes)
            {
                return;
            }

            try
            {
                using var connection = Db.OpenConnection();
                using var command = new SqlCommand("DELETE FROM Products WHERE Article = @article", connection);
                command.Parameters.AddWithValue("@article", article);
                command.ExecuteNonQuery();
                LoadProducts();
            }
            catch
            {
                MessageBox.Show("Нельзя удалить товар, который есть в заказе.", "Ошибка");
            }
        }

        private void exitButton_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}
Модуль 3. Добавление и редактирование товара
1. ProductEditForm
Компоненты:

TextBox articleTextBox
TextBox titleTextBox
ComboBox categoryComboBox
TextBox descriptionTextBox
ComboBox manufacturerComboBox
ComboBox providerComboBox
TextBox priceTextBox
ComboBox unitComboBox
TextBox stockTextBox
TextBox discountTextBox
PictureBox photoBox
Button photoButton
Button saveButton
Button cancelButton
Свойства:

articleTextBox.ReadOnly = True
descriptionTextBox.Multiline = True
photoBox.SizeMode = Zoom

categoryComboBox.DropDownStyle = DropDownList
manufacturerComboBox.DropDownStyle = DropDownList
providerComboBox.DropDownStyle = DropDownList
unitComboBox.DropDownStyle = DropDownList
2. ProductEditForm.cs
using Microsoft.Data.SqlClient;

namespace demo1
{
    public partial class ProductEditForm : Form
    {
        private readonly string article;
        private string photoPath = "";
        private string newPhotoPath = "";

        public ProductEditForm(string article)
        {
            InitializeComponent();
            this.article = article;
        }

        private bool IsEdit => article != "";

        private void ProductEditForm_Load(object sender, EventArgs e)
        {
            LoadComboBoxes();

            if (IsEdit)
            {
                LoadProduct();
            }
            else
            {
                articleLabel.Visible = false;
                articleTextBox.Visible = false;
                photoPath = "picture.png";
                photoBox.Image = Db.GetImage(photoPath);
            }
        }

        private void LoadComboBoxes()
        {
            Db.LoadComboBox(categoryComboBox, "SELECT ProductCategoryId, Title FROM ProductCategories ORDER BY Title", "Title", "ProductCategoryId");
            Db.LoadComboBox(manufacturerComboBox, "SELECT ManufacturerId, Title FROM Manufacturers ORDER BY Title", "Title", "ManufacturerId");
            Db.LoadComboBox(providerComboBox, "SELECT ProviderId, Title FROM Providers ORDER BY Title", "Title", "ProviderId");
            Db.LoadComboBox(unitComboBox, "SELECT UnitId, Title FROM Units ORDER BY Title", "Title", "UnitId");
        }

        private void LoadProduct()
        {
            using var connection = Db.OpenConnection();
            string sql = "SELECT * FROM Products WHERE Article = @article";
            using var command = new SqlCommand(sql, connection);
            command.Parameters.AddWithValue("@article", article);
            using var reader = command.ExecuteReader();

            if (!reader.Read())
            {
                Close();
                return;
            }

            articleTextBox.Text = article;
            titleTextBox.Text = reader["Title"].ToString();
            descriptionTextBox.Text = reader["Description"].ToString();
            priceTextBox.Text = reader["Price"].ToString();
            stockTextBox.Text = reader["StockQuantity"].ToString();
            discountTextBox.Text = reader["Discount"].ToString();

            categoryComboBox.SelectedValue = Convert.ToInt32(reader["ProductCategoryId"]);
            manufacturerComboBox.SelectedValue = Convert.ToInt32(reader["ManufacturerId"]);
            providerComboBox.SelectedValue = Convert.ToInt32(reader["ProviderId"]);
            unitComboBox.SelectedValue = Convert.ToInt32(reader["UnitId"]);

            photoPath = reader["PhotoPath"].ToString()!.Trim();
            photoBox.Image = Db.GetImage(photoPath);
        }

        private void saveButton_Click(object sender, EventArgs e)
        {
            if (!decimal.TryParse(priceTextBox.Text, out decimal price) || price < 0 ||
                !int.TryParse(stockTextBox.Text, out int stock) || stock < 0 ||
                !int.TryParse(discountTextBox.Text, out int discount) || discount < 0 || discount > 100)
            {
                MessageBox.Show("Проверьте цену, количество и скидку.", "Ошибка");
                return;
            }

            if (titleTextBox.Text.Trim() == "")
            {
                MessageBox.Show("Введите наименование товара.", "Ошибка");
                return;
            }

            string newArticle = IsEdit ? article : GetNewArticle();
            string savedPhoto = SavePhoto(newArticle);

            using var connection = Db.OpenConnection();

            string sql = IsEdit ? """
                UPDATE Products SET
                    Title=@title, UnitId=@unit, Price=@price, ProviderId=@provider,
                    ManufacturerId=@manufacturer, ProductCategoryId=@category,
                    Discount=@discount, StockQuantity=@stock,
                    Description=@description, PhotoPath=@photo
                WHERE Article=@article
                """ : """
                INSERT INTO Products
                (Article, Title, UnitId, Price, ProviderId, ManufacturerId, ProductCategoryId,
                 Discount, StockQuantity, Description, PhotoPath)
                VALUES
                (@article, @title, @unit, @price, @provider, @manufacturer, @category,
                 @discount, @stock, @description, @photo)
                """;

            using var command = new SqlCommand(sql, connection);
            command.Parameters.AddWithValue("@article", newArticle);
            command.Parameters.AddWithValue("@title", titleTextBox.Text.Trim());
            command.Parameters.AddWithValue("@unit", unitComboBox.SelectedValue);
            command.Parameters.AddWithValue("@price", price);
            command.Parameters.AddWithValue("@provider", providerComboBox.SelectedValue);
            command.Parameters.AddWithValue("@manufacturer", manufacturerComboBox.SelectedValue);
            command.Parameters.AddWithValue("@category", categoryComboBox.SelectedValue);
            command.Parameters.AddWithValue("@discount", discount);
            command.Parameters.AddWithValue("@stock", stock);
            command.Parameters.AddWithValue("@description", descriptionTextBox.Text.Trim());
            command.Parameters.AddWithValue("@photo", savedPhoto);
            command.ExecuteNonQuery();

            Close();
        }

        private string GetNewArticle()
        {
            using var connection = Db.OpenConnection();
            using var command = new SqlCommand("SELECT COUNT(*) + 1 FROM Products", connection);
            return "NEW" + command.ExecuteScalar();
        }

        private void photoButton_Click(object sender, EventArgs e)
        {
            using var dialog = new OpenFileDialog();
            dialog.Filter = "Изображения|*.jpg;*.jpeg;*.png";

            if (dialog.ShowDialog() == DialogResult.OK)
            {
                newPhotoPath = dialog.FileName;
                using var image = Image.FromFile(newPhotoPath);
                photoBox.Image = new Bitmap(image);
            }
        }

        private string SavePhoto(string currentArticle)
        {
            if (newPhotoPath == "")
            {
                return photoPath;
            }

            string fileName = currentArticle + Path.GetExtension(newPhotoPath);
            string path = Path.Combine(AppContext.BaseDirectory, "Images", fileName);

            using var image = Image.FromFile(newPhotoPath);
            using var small = new Bitmap(image, new Size(300, 200));
            small.Save(path);

            if (IsEdit && photoPath != "" && photoPath != "picture.png" && photoPath != fileName)
            {
                string oldPath = Path.Combine(AppContext.BaseDirectory, "Images", photoPath);
                if (File.Exists(oldPath))
                {
                    File.Delete(oldPath);
                }
            }

            return fileName;
        }

        private void cancelButton_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}
Модуль 4. Карточка заказа
1. OrderCard
Создать:

UserControl OrderCard
Компоненты:

Label infoLabel
Label deliveryLabel
Button editButton
Button deleteButton
2. OrderCard.cs
namespace demo1
{
    public partial class OrderCard : UserControl
    {
        public event Action<int>? EditOrder;
        public event Action<int>? DeleteOrder;

        private int orderId;

        public OrderCard()
        {
            InitializeComponent();
        }

        public void SetOrder(int id, string products, string status, string address,
            DateTime orderDate, DateTime deliveryDate, bool isAdmin)
        {
            orderId = id;
            editButton.Visible = isAdmin;
            deleteButton.Visible = isAdmin;

            infoLabel.Text =
                $"Артикул заказа: {products}\n" +
                $"Статус заказа: {status}\n" +
                $"Адрес пункта выдачи: {address}\n" +
                $"Дата заказа: {orderDate:dd.MM.yyyy}";

            deliveryLabel.Text = $"Дата доставки\n{deliveryDate:dd.MM.yyyy}";
        }

        private void editButton_Click(object sender, EventArgs e)
        {
            EditOrder?.Invoke(orderId);
        }

        private void deleteButton_Click(object sender, EventArgs e)
        {
            DeleteOrder?.Invoke(orderId);
        }
    }
}
Модуль 4. Список заказов
1. OrdersForm
Компоненты:

Button addButton
Button closeButton
FlowLayoutPanel ordersPanel
Свойства:

ordersPanel.AutoScroll = True
ordersPanel.FlowDirection = TopDown
ordersPanel.WrapContents = False
2. OrdersForm.cs
using Microsoft.Data.SqlClient;

namespace demo1
{
    public partial class OrdersForm : Form
    {
        private readonly bool isAdmin;

        public OrdersForm(bool isAdmin)
        {
            InitializeComponent();
            this.isAdmin = isAdmin;
        }

        private void OrdersForm_Load(object sender, EventArgs e)
        {
            addButton.Visible = isAdmin;
            LoadOrders();
        }

        private void LoadOrders()
        {
            ordersPanel.Controls.Clear();

            using var connection = Db.OpenConnection();

            string sql = """
                SELECT o.OrderId, o.OrderDate, o.DeliveryDate,
                       pp.Address, os.Title AS Status,
                       (SELECT STRING_AGG(Article, ', ')
                        FROM OrderProducts
                        WHERE OrderId = o.OrderId) AS Products
                FROM Orders o
                JOIN PickupPoints pp ON o.PickupPointId = pp.PickupPointId
                JOIN OrderStatuses os ON o.OrderStatusId = os.OrderStatusId
                ORDER BY o.OrderId
                """;

            using var command = new SqlCommand(sql, connection);
            using var reader = command.ExecuteReader();

            while (reader.Read())
            {
                var card = new OrderCard();

                card.SetOrder(
                    Convert.ToInt32(reader["OrderId"]),
                    reader["Products"].ToString()!,
                    reader["Status"].ToString()!,
                    reader["Address"].ToString()!,
                    Convert.ToDateTime(reader["OrderDate"]),
                    Convert.ToDateTime(reader["DeliveryDate"]),
                    isAdmin);

                card.EditOrder += OpenEditForm;
                card.DeleteOrder += DeleteOrder;
                ordersPanel.Controls.Add(card);
            }
        }

        private void addButton_Click(object sender, EventArgs e)
        {
            OpenEditForm(0);
        }

        private void OpenEditForm(int orderId)
        {
            using var form = new OrderEditForm(orderId);
            form.ShowDialog();
            LoadOrders();
        }

        private void DeleteOrder(int orderId)
        {
            if (MessageBox.Show("Удалить заказ?", "Подтверждение", MessageBoxButtons.YesNo) != DialogResult.Yes)
            {
                return;
            }

            using var connection = Db.OpenConnection();
            using var command = new SqlCommand(
                "DELETE FROM OrderProducts WHERE OrderId=@id; DELETE FROM Orders WHERE OrderId=@id",
                connection);

            command.Parameters.AddWithValue("@id", orderId);
            command.ExecuteNonQuery();
            LoadOrders();
        }

        private void closeButton_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}
Модуль 4. Добавление и редактирование заказа
1. OrderEditForm
Компоненты:

ComboBox articleComboBox
ComboBox statusComboBox
ComboBox pickupComboBox
DateTimePicker orderDatePicker
DateTimePicker deliveryDatePicker
Button saveButton
Button cancelButton
Свойства:

articleComboBox.DropDownStyle = DropDownList
statusComboBox.DropDownStyle = DropDownList
pickupComboBox.DropDownStyle = DropDownList
2. OrderEditForm.cs
using Microsoft.Data.SqlClient;

namespace demo1
{
    public partial class OrderEditForm : Form
    {
        private readonly int orderId;

        public OrderEditForm(int orderId)
        {
            InitializeComponent();
            this.orderId = orderId;
        }

        private bool IsEdit => orderId != 0;

        private void OrderEditForm_Load(object sender, EventArgs e)
        {
            Db.LoadComboBox(articleComboBox, "SELECT Article FROM Products ORDER BY Article", "Article", "Article");
            Db.LoadComboBox(statusComboBox, "SELECT OrderStatusId, Title FROM OrderStatuses ORDER BY Title", "Title", "OrderStatusId");
            Db.LoadComboBox(pickupComboBox, "SELECT PickupPointId, Address FROM PickupPoints ORDER BY PickupPointId", "Address", "PickupPointId");

            if (IsEdit)
            {
                LoadOrder();
            }
        }

        private void LoadOrder()
        {
            using var connection = Db.OpenConnection();

            string sql = """
                SELECT o.*, (SELECT TOP 1 Article FROM OrderProducts WHERE OrderId=o.OrderId) AS Article
                FROM Orders o
                WHERE o.OrderId=@id
                """;

            using var command = new SqlCommand(sql, connection);
            command.Parameters.AddWithValue("@id", orderId);

            using var reader = command.ExecuteReader();
            if (!reader.Read())
            {
                Close();
                return;
            }

            articleComboBox.SelectedValue = reader["Article"].ToString() ?? "";
            statusComboBox.SelectedValue = Convert.ToInt32(reader["OrderStatusId"]);
            pickupComboBox.SelectedValue = Convert.ToInt32(reader["PickupPointId"]);
            orderDatePicker.Value = Convert.ToDateTime(reader["OrderDate"]);
            deliveryDatePicker.Value = Convert.ToDateTime(reader["DeliveryDate"]);
        }

        private void saveButton_Click(object sender, EventArgs e)
        {
            int id = IsEdit ? orderId : NewOrderId();
            string article = articleComboBox.SelectedValue?.ToString() ?? "";

            using var connection = Db.OpenConnection();

            string sql = IsEdit ? """
                UPDATE Orders SET OrderDate=@orderDate, DeliveryDate=@deliveryDate,
                    PickupPointId=@point, OrderStatusId=@status
                WHERE OrderId=@id;

                DELETE FROM OrderProducts WHERE OrderId=@id;

                INSERT INTO OrderProducts(OrderId, Article, Quantity)
                VALUES(@id, @article, 1);
                """ : """
                INSERT INTO Orders(OrderId, OrderDate, DeliveryDate, PickupPointId, UserId, ReceiptCode, OrderStatusId)
                VALUES(@id, @orderDate, @deliveryDate, @point, NULL, @code, @status);

                INSERT INTO OrderProducts(OrderId, Article, Quantity)
                VALUES(@id, @article, 1);
                """;

            using var command = new SqlCommand(sql, connection);
            command.Parameters.AddWithValue("@id", id);
            command.Parameters.AddWithValue("@orderDate", orderDatePicker.Value.Date);
            command.Parameters.AddWithValue("@deliveryDate", deliveryDatePicker.Value.Date);
            command.Parameters.AddWithValue("@point", pickupComboBox.SelectedValue);
            command.Parameters.AddWithValue("@status", statusComboBox.SelectedValue);
            command.Parameters.AddWithValue("@article", article);
            command.Parameters.AddWithValue("@code", (900 + id).ToString());
            command.ExecuteNonQuery();

            Close();
        }

        private int NewOrderId()
        {
            using var connection = Db.OpenConnection();
            using var command = new SqlCommand("SELECT ISNULL(MAX(OrderId), 0) + 1 FROM Orders", connection);
            return Convert.ToInt32(command.ExecuteScalar());
        }

        private void cancelButton_Click(object sender, EventArgs e)
        {
            Close();
        }
    }
}
Что учить как шаблон
Открыть подключение
using var connection = Db.OpenConnection();
SELECT
using var command = new SqlCommand(sql, connection);
using var reader = command.ExecuteReader();

while (reader.Read())
{
}
INSERT / UPDATE / DELETE
using var command = new SqlCommand(sql, connection);
command.Parameters.AddWithValue("@id", id);
command.ExecuteNonQuery();
ComboBox
Db.LoadComboBox(comboBox, "SELECT Id, Title FROM Table", "Title", "Id");
Картинка
Db.GetImage(fileName)
Одна форма на добавление и редактирование
new ProductEditForm("")       // добавить товар
new ProductEditForm(article)  // редактировать товар

new OrderEditForm(0)          // добавить заказ
new OrderEditForm(orderId)    // редактировать заказ
Главное правило проекта:

Form1 -> вход
ProductForm -> список товаров
ProductCard -> карточка товара
ProductEditForm -> товар
OrdersForm -> список заказов
OrderCard -> карточка заказа
OrderEditForm -> заказ
Db -> общие методы