Thanh toán hóa đơn trong phần mềm Quản lý quán cafe với C# Winform

Không có gì tuyệt vời hơn là luyện tập với ví dụ thực tế. Nào cùng nhau thử thách bản thân với phần mềm: Quản lý quán cafe

Bạn nên có kiến thức về:

• Lập trình Winform cơ bản
• Delegate – Event
• SQL server
• Xử lý ngày tháng năm

Code Data.sql

CREATE DATABASE QuanLyQuanCafe
GO

USE QuanLyQuanCafe
GO

-- Food
-- Table
-- FoodCategory
-- Account
-- Bill
-- BillInfo

CREATE TABLE TableFood
(
	id INT IDENTITY PRIMARY KEY,
	name NVARCHAR(100) NOT NULL DEFAULT N'Bàn chưa có tên',
	status NVARCHAR(100) NOT NULL DEFAULT N'Trống'	-- Trống || Có người
)
GO

CREATE TABLE Account
(
	UserName NVARCHAR(100) PRIMARY KEY,	
	DisplayName NVARCHAR(100) NOT NULL DEFAULT N'Kter',
	PassWord NVARCHAR(1000) NOT NULL DEFAULT 0,
	Type INT NOT NULL  DEFAULT 0 -- 1: admin && 0: staff
)
GO

CREATE TABLE FoodCategory
(
	id INT IDENTITY PRIMARY KEY,
	name NVARCHAR(100) NOT NULL DEFAULT N'Chưa đặt tên'
)
GO

CREATE TABLE Food
(
	id INT IDENTITY PRIMARY KEY,
	name NVARCHAR(100) NOT NULL DEFAULT N'Chưa đặt tên',
	idCategory INT NOT NULL,
	price FLOAT NOT NULL DEFAULT 0
	
	FOREIGN KEY (idCategory) REFERENCES dbo.FoodCategory(id)
)
GO

CREATE TABLE Bill
(
	id INT IDENTITY PRIMARY KEY,
	DateCheckIn DATE NOT NULL DEFAULT GETDATE(),
	DateCheckOut DATE,
	idTable INT NOT NULL,
	status INT NOT NULL DEFAULT 0 -- 1: đã thanh toán && 0: chưa thanh toán
	
	FOREIGN KEY (idTable) REFERENCES dbo.TableFood(id)
)
GO

CREATE TABLE BillInfo
(
	id INT IDENTITY PRIMARY KEY,
	idBill INT NOT NULL,
	idFood INT NOT NULL,
	count INT NOT NULL DEFAULT 0
	
	FOREIGN KEY (idBill) REFERENCES dbo.Bill(id),
	FOREIGN KEY (idFood) REFERENCES dbo.Food(id)
)
GO

INSERT INTO dbo.Account
        ( UserName ,
          DisplayName ,
          PassWord ,
          Type
        )
VALUES  ( N'K9' , -- UserName - nvarchar(100)
          N'RongK9' , -- DisplayName - nvarchar(100)
          N'1' , -- PassWord - nvarchar(1000)
          1  -- Type - int
        )
INSERT INTO dbo.Account
        ( UserName ,
          DisplayName ,
          PassWord ,
          Type
        )
VALUES  ( N'staff' , -- UserName - nvarchar(100)
          N'staff' , -- DisplayName - nvarchar(100)
          N'1' , -- PassWord - nvarchar(1000)
          0  -- Type - int
        )
GO

CREATE PROC USP_GetAccountByUserName
@userName nvarchar(100)
AS 
BEGIN
	SELECT * FROM dbo.Account WHERE UserName = @userName
END
GO

EXEC dbo.USP_GetAccountByUserName @userName = N'k9' -- nvarchar(100)

GO

CREATE PROC USP_Login
@userName nvarchar(100), @passWord nvarchar(100)
AS
BEGIN
	SELECT * FROM dbo.Account WHERE UserName = @userName AND PassWord = @passWord
END
GO

-- thêm bàn
DECLARE @i INT = 0

WHILE @i <= 10
BEGIN
	INSERT dbo.TableFood ( name)VALUES  ( N'Bàn ' + CAST(@i AS nvarchar(100)))
	SET @i = @i + 1
END
GO

CREATE PROC USP_GetTableList
AS SELECT * FROM dbo.TableFood
GO

UPDATE dbo.TableFood SET STATUS = N'Có người' WHERE id = 9

EXEC dbo.USP_GetTableList
GO

-- thêm category
INSERT dbo.FoodCategory
        ( name )
VALUES  ( N'Hải sản'  -- name - nvarchar(100)
          )
INSERT dbo.FoodCategory
        ( name )
VALUES  ( N'Nông sản' )
INSERT dbo.FoodCategory
        ( name )
VALUES  ( N'Lâm sản' )
INSERT dbo.FoodCategory
        ( name )
VALUES  ( N'Sản sản' )
INSERT dbo.FoodCategory
        ( name )
VALUES  ( N'Nước' )

-- thêm món ăn
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Mực một nắng nước sa tế', -- name - nvarchar(100)
          1, -- idCategory - int
          120000)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Nghêu hấp xả', 1, 50000)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Dú dê nướng sữa', 2, 60000)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Heo rừng nướng muối ớt', 3, 75000)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Cơm chiên mushi', 4, 999999)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'7Up', 5, 15000)
INSERT dbo.Food
        ( name, idCategory, price )
VALUES  ( N'Cafe', 5, 12000)

-- thêm bill
INSERT	dbo.Bill
        ( DateCheckIn ,
          DateCheckOut ,
          idTable ,
          status
        )
VALUES  ( GETDATE() , -- DateCheckIn - date
          NULL , -- DateCheckOut - date
          3 , -- idTable - int
          0  -- status - int
        )
        
INSERT	dbo.Bill
        ( DateCheckIn ,
          DateCheckOut ,
          idTable ,
          status
        )
VALUES  ( GETDATE() , -- DateCheckIn - date
          NULL , -- DateCheckOut - date
          4, -- idTable - int
          0  -- status - int
        )
INSERT	dbo.Bill
        ( DateCheckIn ,
          DateCheckOut ,
          idTable ,
          status
        )
VALUES  ( GETDATE() , -- DateCheckIn - date
          GETDATE() , -- DateCheckOut - date
          5 , -- idTable - int
          1  -- status - int
        )

-- thêm bill info
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 5, -- idBill - int
          1, -- idFood - int
          2  -- count - int
          )
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 5, -- idBill - int
          3, -- idFood - int
          4  -- count - int
          )
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 5, -- idBill - int
          5, -- idFood - int
          1  -- count - int
          )
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 6, -- idBill - int
          1, -- idFood - int
          2  -- count - int
          )
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 6, -- idBill - int
          6, -- idFood - int
          2  -- count - int
          )
INSERT	dbo.BillInfo
        ( idBill, idFood, count )
VALUES  ( 7, -- idBill - int
          5, -- idFood - int
          2  -- count - int
          )         
          
GO

CREATE PROC USP_InsertBill
@idTable INT
AS
BEGIN
	INSERT dbo.Bill 
	        ( DateCheckIn ,
	          DateCheckOut ,
	          idTable ,
	          status
	        )
	VALUES  ( GETDATE() , -- DateCheckIn - date
	          NULL , -- DateCheckOut - date
	          @idTable , -- idTable - int
	          0  -- status - int
	        )
END
GO

CREATE PROC USP_InsertBillInfo
@idBill INT, @idFood INT, @count INT
AS
BEGIN

	DECLARE @isExitsBillInfo INT
	DECLARE @foodCount INT = 1
	
	SELECT @isExitsBillInfo = id, @foodCount = b.count 
	FROM dbo.BillInfo AS b 
	WHERE idBill = @idBill AND idFood = @idFood

	IF (@isExitsBillInfo > 0)
	BEGIN
		DECLARE @newCount INT = @foodCount + @count
		IF (@newCount > 0)
			UPDATE dbo.BillInfo	SET count = @foodCount + @count WHERE idFood = @idFood
		ELSE
			DELETE dbo.BillInfo WHERE idBill = @idBill AND idFood = @idFood
	END
	ELSE
	BEGIN
		INSERT	dbo.BillInfo
        ( idBill, idFood, count )
		VALUES  ( @idBill, -- idBill - int
          @idFood, -- idFood - int
          @count  -- count - int
          )
	END
END
GO

DELETE dbo.BillInfo

DELETE dbo.Bill

CREATE TRIGGER UTG_UpdateBillInfo
ON dbo.BillInfo FOR INSERT, UPDATE
AS
BEGIN
	DECLARE @idBill INT
	
	SELECT @idBill = idBill FROM Inserted
	
	DECLARE @idTable INT
	
	SELECT @idTable = idTable FROM dbo.Bill WHERE id = @idBill AND status = 0
	
	UPDATE dbo.TableFood SET status = N'Có người' WHERE id = @idTable
END
GO

CREATE TRIGGER UTG_UpdateBill
ON dbo.Bill FOR UPDATE
AS
BEGIN
	DECLARE @idBill INT
	
	SELECT @idBill = id FROM Inserted	
	
	DECLARE @idTable INT
	
	SELECT @idTable = idTable FROM dbo.Bill WHERE id = @idBill
	
	DECLARE @count int = 0
	
	SELECT @count = COUNT(*) FROM dbo.Bill WHERE idTable = @idTable AND status = 0
	
	IF (@count = 0)
		UPDATE dbo.TableFood SET status = N'Trống' WHERE id = @idTable
END
GO

Code fTableManager.cs

using QuanLyQuanCafe.DAO;
using QuanLyQuanCafe.DTO;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace QuanLyQuanCafe
{
    public partial class fTableManager : Form
    {
        public fTableManager()
        {
            InitializeComponent();

            LoadTable();
            LoadCategory();
        }

        #region Method

        void LoadCategory()
        {
            List<Category> listCategory = CategoryDAO.Instance.GetListCategory();
            cbCategory.DataSource = listCategory;
            cbCategory.DisplayMember = "Name";
        }

        void LoadFoodListByCategoryID(int id)
        {
            List<Food> listFood = FoodDAO.Instance.GetFoodByCategoryID(id);
            cbFood.DataSource = listFood;
            cbFood.DisplayMember = "Name";
        }
        void LoadTable()
        {
            flpTable.Controls.Clear();
            
            List<Table> tableList = TableDAO.Instance.LoadTableList();

            foreach (Table item in tableList)
            {
                Button btn = new Button() { Width = TableDAO.TableWidth, Height = TableDAO.TableHeight};
                btn.Text = item.Name + Environment.NewLine + item.Status;
                btn.Click += btn_Click;
                btn.Tag = item;

                switch (item.Status)
                {
                    case "Trống":
                        btn.BackColor = Color.Aqua;
                        break;
                    default:
                        btn.BackColor = Color.LightPink;
                        break;
                }

                flpTable.Controls.Add(btn);
            }
        }

        void ShowBill(int id)
        {
            lsvBill.Items.Clear();
            List<QuanLyQuanCafe.DTO.Menu> listBillInfo = MenuDAO.Instance.GetListMenuByTable(id);
            float totalPrice = 0;
            foreach (QuanLyQuanCafe.DTO.Menu item in listBillInfo)
            {
                ListViewItem lsvItem = new ListViewItem(item.FoodName.ToString());
                lsvItem.SubItems.Add(item.Count.ToString());
                lsvItem.SubItems.Add(item.Price.ToString());
                lsvItem.SubItems.Add(item.TotalPrice.ToString());
                totalPrice += item.TotalPrice;
                lsvBill.Items.Add(lsvItem);
            }
            CultureInfo culture = new CultureInfo("vi-VN");

            //Thread.CurrentThread.CurrentCulture = culture;

            txbTotalPrice.Text = totalPrice.ToString("c", culture);

        }

        #endregion


        #region Events
        void btn_Click(object sender, EventArgs e)
        {
            int tableID = ((sender as Button).Tag as Table).ID;
            lsvBill.Tag = (sender as Button).Tag;
            ShowBill(tableID);
        }
        private void đăngXuấtToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void thôngTinCáNhânToolStripMenuItem_Click(object sender, EventArgs e)
        {
            fAccountProfile f = new fAccountProfile();
            f.ShowDialog();
        }

        private void adminToolStripMenuItem_Click(object sender, EventArgs e)
        {
            fAdmin f = new fAdmin();
            f.ShowDialog();
        }

        private void cbCategory_SelectedIndexChanged(object sender, EventArgs e)
        {
            int id = 0;

            ComboBox cb = sender as ComboBox;

            if (cb.SelectedItem == null)
                return;

            Category selected = cb.SelectedItem as Category;
            id = selected.ID;

            LoadFoodListByCategoryID(id);
        }

        private void btnAddFood_Click(object sender, EventArgs e)
        {
            Table table = lsvBill.Tag as Table;

            int idBill = BillDAO.Instance.GetUncheckBillIDByTableID(table.ID);
            int foodID = (cbFood.SelectedItem as Food).ID;
            int count = (int)nmFoodCount.Value;

            if (idBill == -1)
            {
                BillDAO.Instance.InsertBill(table.ID);
                BillInfoDAO.Instance.InsertBillInfo(BillDAO.Instance.GetMaxIDBill(), foodID , count);
            }
            else
            {
                BillInfoDAO.Instance.InsertBillInfo(idBill, foodID, count);
            }

            ShowBill(table.ID);

            LoadTable();
        }        
        private void btnCheckOut_Click(object sender, EventArgs e)
        {
            Table table = lsvBill.Tag as Table;

            int idBill = BillDAO.Instance.GetUncheckBillIDByTableID(table.ID);

            if (idBill != -1)
            {
                if (MessageBox.Show("Bạn có chắc thanh toán hóa đơn cho bàn " + table.Name, "Thông báo", MessageBoxButtons.OKCancel) == System.Windows.Forms.DialogResult.OK)
                {
                    BillDAO.Instance.CheckOut(idBill);
                    ShowBill(table.ID);

                    LoadTable();
                }
            }
        }

        #endregion        

    }
}

Code fTableManager.Designer.cs

namespace QuanLyQuanCafe
{
    partial class fTableManager
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.menuStrip1 = new System.Windows.Forms.MenuStrip();
            this.adminToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
            this.thôngTinTàiKhoảnToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
            this.thôngTinCáNhânToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
            this.đăngXuấtToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
            this.panel2 = new System.Windows.Forms.Panel();
            this.lsvBill = new System.Windows.Forms.ListView();
            this.columnHeader1 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.columnHeader2 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.columnHeader3 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.columnHeader4 = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.panel3 = new System.Windows.Forms.Panel();
            this.txbTotalPrice = new System.Windows.Forms.TextBox();
            this.cbSwitchTable = new System.Windows.Forms.ComboBox();
            this.btnSwitchTable = new System.Windows.Forms.Button();
            this.nmDisCount = new System.Windows.Forms.NumericUpDown();
            this.btnDiscount = new System.Windows.Forms.Button();
            this.btnCheckOut = new System.Windows.Forms.Button();
            this.panel4 = new System.Windows.Forms.Panel();
            this.nmFoodCount = new System.Windows.Forms.NumericUpDown();
            this.btnAddFood = new System.Windows.Forms.Button();
            this.cbFood = new System.Windows.Forms.ComboBox();
            this.cbCategory = new System.Windows.Forms.ComboBox();
            this.flpTable = new System.Windows.Forms.FlowLayoutPanel();
            this.menuStrip1.SuspendLayout();
            this.panel2.SuspendLayout();
            this.panel3.SuspendLayout();
            ((System.ComponentModel.ISupportInitialize)(this.nmDisCount)).BeginInit();
            this.panel4.SuspendLayout();
            ((System.ComponentModel.ISupportInitialize)(this.nmFoodCount)).BeginInit();
            this.SuspendLayout();
            // 
            // menuStrip1
            // 
            this.menuStrip1.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
            this.adminToolStripMenuItem,
            this.thôngTinTàiKhoảnToolStripMenuItem});
            this.menuStrip1.Location = new System.Drawing.Point(0, 0);
            this.menuStrip1.Name = "menuStrip1";
            this.menuStrip1.Size = new System.Drawing.Size(797, 24);
            this.menuStrip1.TabIndex = 1;
            this.menuStrip1.Text = "menuStrip1";
            // 
            // adminToolStripMenuItem
            // 
            this.adminToolStripMenuItem.Name = "adminToolStripMenuItem";
            this.adminToolStripMenuItem.Size = new System.Drawing.Size(55, 20);
            this.adminToolStripMenuItem.Text = "Admin";
            this.adminToolStripMenuItem.Click += new System.EventHandler(this.adminToolStripMenuItem_Click);
            // 
            // thôngTinTàiKhoảnToolStripMenuItem
            // 
            this.thôngTinTàiKhoảnToolStripMenuItem.DropDownItems.AddRange(new System.Windows.Forms.ToolStripItem[] {
            this.thôngTinCáNhânToolStripMenuItem,
            this.đăngXuấtToolStripMenuItem});
            this.thôngTinTàiKhoảnToolStripMenuItem.Name = "thôngTinTàiKhoảnToolStripMenuItem";
            this.thôngTinTàiKhoảnToolStripMenuItem.Size = new System.Drawing.Size(123, 20);
            this.thôngTinTàiKhoảnToolStripMenuItem.Text = "Thông tin tài khoản";
            // 
            // thôngTinCáNhânToolStripMenuItem
            // 
            this.thôngTinCáNhânToolStripMenuItem.Name = "thôngTinCáNhânToolStripMenuItem";
            this.thôngTinCáNhânToolStripMenuItem.Size = new System.Drawing.Size(171, 22);
            this.thôngTinCáNhânToolStripMenuItem.Text = "Thông tin cá nhân";
            this.thôngTinCáNhânToolStripMenuItem.Click += new System.EventHandler(this.thôngTinCáNhânToolStripMenuItem_Click);
            // 
            // đăngXuấtToolStripMenuItem
            // 
            this.đăngXuấtToolStripMenuItem.Name = "đăngXuấtToolStripMenuItem";
            this.đăngXuấtToolStripMenuItem.Size = new System.Drawing.Size(171, 22);
            this.đăngXuấtToolStripMenuItem.Text = "Đăng xuất";
            this.đăngXuấtToolStripMenuItem.Click += new System.EventHandler(this.đăngXuấtToolStripMenuItem_Click);
            // 
            // panel2
            // 
            this.panel2.Controls.Add(this.lsvBill);
            this.panel2.Location = new System.Drawing.Point(447, 85);
            this.panel2.Name = "panel2";
            this.panel2.Size = new System.Drawing.Size(338, 315);
            this.panel2.TabIndex = 2;
            // 
            // lsvBill
            // 
            this.lsvBill.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
            this.columnHeader1,
            this.columnHeader2,
            this.columnHeader3,
            this.columnHeader4});
            this.lsvBill.GridLines = true;
            this.lsvBill.Location = new System.Drawing.Point(3, 3);
            this.lsvBill.Name = "lsvBill";
            this.lsvBill.Size = new System.Drawing.Size(332, 309);
            this.lsvBill.TabIndex = 0;
            this.lsvBill.UseCompatibleStateImageBehavior = false;
            this.lsvBill.View = System.Windows.Forms.View.Details;
            // 
            // columnHeader1
            // 
            this.columnHeader1.Text = "Tên món";
            this.columnHeader1.Width = 133;
            // 
            // columnHeader2
            // 
            this.columnHeader2.Text = "Số lượng";
            // 
            // columnHeader3
            // 
            this.columnHeader3.Text = "Đơn giá";
            this.columnHeader3.Width = 54;
            // 
            // columnHeader4
            // 
            this.columnHeader4.Text = "Thành tiền";
            this.columnHeader4.Width = 81;
            // 
            // panel3
            // 
            this.panel3.Controls.Add(this.txbTotalPrice);
            this.panel3.Controls.Add(this.cbSwitchTable);
            this.panel3.Controls.Add(this.btnSwitchTable);
            this.panel3.Controls.Add(this.nmDisCount);
            this.panel3.Controls.Add(this.btnDiscount);
            this.panel3.Controls.Add(this.btnCheckOut);
            this.panel3.Location = new System.Drawing.Point(447, 406);
            this.panel3.Name = "panel3";
            this.panel3.Size = new System.Drawing.Size(338, 52);
            this.panel3.TabIndex = 3;
            // 
            // txbTotalPrice
            // 
            this.txbTotalPrice.Font = new System.Drawing.Font("Arial", 11.25F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(163)));
            this.txbTotalPrice.ForeColor = System.Drawing.Color.OrangeRed;
            this.txbTotalPrice.Location = new System.Drawing.Point(164, 17);
            this.txbTotalPrice.Name = "txbTotalPrice";
            this.txbTotalPrice.ReadOnly = true;
            this.txbTotalPrice.Size = new System.Drawing.Size(90, 25);
            this.txbTotalPrice.TabIndex = 7;
            this.txbTotalPrice.Text = "0";
            this.txbTotalPrice.TextAlign = System.Windows.Forms.HorizontalAlignment.Right;
            // 
            // cbSwitchTable
            // 
            this.cbSwitchTable.FormattingEnabled = true;
            this.cbSwitchTable.Location = new System.Drawing.Point(3, 28);
            this.cbSwitchTable.Name = "cbSwitchTable";
            this.cbSwitchTable.Size = new System.Drawing.Size(75, 21);
            this.cbSwitchTable.TabIndex = 6;
            // 
            // btnSwitchTable
            // 
            this.btnSwitchTable.Location = new System.Drawing.Point(3, 3);
            this.btnSwitchTable.Name = "btnSwitchTable";
            this.btnSwitchTable.Size = new System.Drawing.Size(75, 26);
            this.btnSwitchTable.TabIndex = 5;
            this.btnSwitchTable.Text = "Chuyển bàn";
            this.btnSwitchTable.UseVisualStyleBackColor = true;
            // 
            // nmDisCount
            // 
            this.nmDisCount.Location = new System.Drawing.Point(84, 29);
            this.nmDisCount.Name = "nmDisCount";
            this.nmDisCount.Size = new System.Drawing.Size(74, 20);
            this.nmDisCount.TabIndex = 4;
            this.nmDisCount.TextAlign = System.Windows.Forms.HorizontalAlignment.Center;
            // 
            // btnDiscount
            // 
            this.btnDiscount.Location = new System.Drawing.Point(84, 3);
            this.btnDiscount.Name = "btnDiscount";
            this.btnDiscount.Size = new System.Drawing.Size(75, 26);
            this.btnDiscount.TabIndex = 4;
            this.btnDiscount.Text = "Giảm giá";
            this.btnDiscount.UseVisualStyleBackColor = true;
            // 
            // btnCheckOut
            // 
            this.btnCheckOut.Location = new System.Drawing.Point(260, 3);
            this.btnCheckOut.Name = "btnCheckOut";
            this.btnCheckOut.Size = new System.Drawing.Size(75, 46);
            this.btnCheckOut.TabIndex = 3;
            this.btnCheckOut.Text = "Thanh toán";
            this.btnCheckOut.UseVisualStyleBackColor = true;
            this.btnCheckOut.Click += new System.EventHandler(this.btnCheckOut_Click);
            // 
            // panel4
            // 
            this.panel4.Controls.Add(this.nmFoodCount);
            this.panel4.Controls.Add(this.btnAddFood);
            this.panel4.Controls.Add(this.cbFood);
            this.panel4.Controls.Add(this.cbCategory);
            this.panel4.Location = new System.Drawing.Point(447, 27);
            this.panel4.Name = "panel4";
            this.panel4.Size = new System.Drawing.Size(338, 52);
            this.panel4.TabIndex = 4;
            // 
            // nmFoodCount
            // 
            this.nmFoodCount.Location = new System.Drawing.Point(296, 19);
            this.nmFoodCount.Minimum = new decimal(new int[] {
            100,
            0,
            0,
            -2147483648});
            this.nmFoodCount.Name = "nmFoodCount";
            this.nmFoodCount.Size = new System.Drawing.Size(39, 20);
            this.nmFoodCount.TabIndex = 3;
            this.nmFoodCount.Value = new decimal(new int[] {
            1,
            0,
            0,
            0});
            // 
            // btnAddFood
            // 
            this.btnAddFood.Location = new System.Drawing.Point(214, 3);
            this.btnAddFood.Name = "btnAddFood";
            this.btnAddFood.Size = new System.Drawing.Size(75, 46);
            this.btnAddFood.TabIndex = 2;
            this.btnAddFood.Text = "Thêm món";
            this.btnAddFood.UseVisualStyleBackColor = true;
            this.btnAddFood.Click += new System.EventHandler(this.btnAddFood_Click);
            // 
            // cbFood
            // 
            this.cbFood.FormattingEnabled = true;
            this.cbFood.Location = new System.Drawing.Point(3, 28);
            this.cbFood.Name = "cbFood";
            this.cbFood.Size = new System.Drawing.Size(205, 21);
            this.cbFood.TabIndex = 1;
            // 
            // cbCategory
            // 
            this.cbCategory.FormattingEnabled = true;
            this.cbCategory.Location = new System.Drawing.Point(3, 3);
            this.cbCategory.Name = "cbCategory";
            this.cbCategory.Size = new System.Drawing.Size(205, 21);
            this.cbCategory.TabIndex = 0;
            this.cbCategory.SelectedIndexChanged += new System.EventHandler(this.cbCategory_SelectedIndexChanged);
            // 
            // flpTable
            // 
            this.flpTable.AutoScroll = true;
            this.flpTable.Location = new System.Drawing.Point(12, 30);
            this.flpTable.Name = "flpTable";
            this.flpTable.Size = new System.Drawing.Size(429, 428);
            this.flpTable.TabIndex = 5;
            // 
            // fTableManager
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(797, 470);
            this.Controls.Add(this.flpTable);
            this.Controls.Add(this.panel4);
            this.Controls.Add(this.panel3);
            this.Controls.Add(this.panel2);
            this.Controls.Add(this.menuStrip1);
            this.MainMenuStrip = this.menuStrip1;
            this.Name = "fTableManager";
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
            this.Text = "Phần mềm quản lý quán cafe";
            this.menuStrip1.ResumeLayout(false);
            this.menuStrip1.PerformLayout();
            this.panel2.ResumeLayout(false);
            this.panel3.ResumeLayout(false);
            this.panel3.PerformLayout();
            ((System.ComponentModel.ISupportInitialize)(this.nmDisCount)).EndInit();
            this.panel4.ResumeLayout(false);
            ((System.ComponentModel.ISupportInitialize)(this.nmFoodCount)).EndInit();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.MenuStrip menuStrip1;
        private System.Windows.Forms.ToolStripMenuItem adminToolStripMenuItem;
        private System.Windows.Forms.ToolStripMenuItem thôngTinTàiKhoảnToolStripMenuItem;
        private System.Windows.Forms.ToolStripMenuItem thôngTinCáNhânToolStripMenuItem;
        private System.Windows.Forms.ToolStripMenuItem đăngXuấtToolStripMenuItem;
        private System.Windows.Forms.Panel panel2;
        private System.Windows.Forms.ListView lsvBill;
        private System.Windows.Forms.Panel panel3;
        private System.Windows.Forms.Panel panel4;
        private System.Windows.Forms.NumericUpDown nmFoodCount;
        private System.Windows.Forms.Button btnAddFood;
        private System.Windows.Forms.ComboBox cbFood;
        private System.Windows.Forms.ComboBox cbCategory;
        private System.Windows.Forms.ComboBox cbSwitchTable;
        private System.Windows.Forms.Button btnSwitchTable;
        private System.Windows.Forms.NumericUpDown nmDisCount;
        private System.Windows.Forms.Button btnDiscount;
        private System.Windows.Forms.Button btnCheckOut;
        private System.Windows.Forms.FlowLayoutPanel flpTable;
        private System.Windows.Forms.ColumnHeader columnHeader1;
        private System.Windows.Forms.ColumnHeader columnHeader2;
        private System.Windows.Forms.ColumnHeader columnHeader3;
        private System.Windows.Forms.ColumnHeader columnHeader4;
        private System.Windows.Forms.TextBox txbTotalPrice;
    }
}

Code BillDAO.cs

using QuanLyQuanCafe.DTO;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace QuanLyQuanCafe.DAO
{
    public class BillDAO
    {
        private static BillDAO instance;

        public static BillDAO Instance
        {
            get { if (instance == null) instance = new BillDAO(); return BillDAO.instance; }
            private set { BillDAO.instance = value; }
        }

        private BillDAO() { }

        /// <summary>
        /// Thành công: bill ID
        /// thất bại: -1
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public int GetUncheckBillIDByTableID(int id)
        {
            DataTable data = DataProvider.Instance.ExecuteQuery("SELECT * FROM dbo.Bill WHERE idTable = " + id +" AND status = 0");

            if (data.Rows.Count > 0)
            {
                Bill bill = new Bill(data.Rows[0]);
                return bill.ID;
            }

            return -1;
        }

        public void CheckOut(int id)
        {
            string query = "UPDATE dbo.Bill SET status = 1 WHERE id = " + id;
            DataProvider.Instance.ExecuteNonQuery(query);
        }
        public void InsertBill(int id)
        {
            DataProvider.Instance.ExecuteNonQuery("exec USP_InsertBill @idTable", new object[]{id});
        }

        public int GetMaxIDBill()
        {
            try
            {
                return (int)DataProvider.Instance.ExecuteScalar("SELECT MAX(id) FROM dbo.Bill");
            }
            catch
            {
                return 1;
            }
        }
    }
}

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