C# with Access DB - 达到临界水平时将警报框放入库存

Question

我想在我的库存系统中添加一个功能，当程序检测到数据库中的项目数量低于 15 时，会出现一个警告消息框。我不知道是什么 method/command使用方法和放置位置。

这是我的代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;

namespace inventoryForm
{
    public partial class inventory : Form
    {
        private OleDbConnection connection = new OleDbConnection();
        public inventory()
        {
            InitializeComponent();
            connection.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Eziera Yvanne\Documents\Inventory.accdb; Persist Security Info = False";

        }
        private void inventory_Load(object sender, EventArgs e)
        {
        try
        {
            connection.Open();
            OleDbCommand command = new OleDbCommand();
            command.Connection = connection;
            string query = "select * from Inventory";
            command.CommandText = query;

            // Load Inventory table to ComboBox
            OleDbDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                combo_items.Items.Add(reader["Item"].ToString());
            }
            connection.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error " + ex);
        }
    }

    //  Inventory ComboBox
    private void combo_inventory_SelectedIndexChanged(object sender, EventArgs e)
    {
        try
        {
            connection.Open();
            OleDbCommand command = new OleDbCommand();
            command.Connection = connection;
            string query = "select * from Inventory where Item='" + combo_items.Text + "'";
            command.CommandText = query;

            OleDbDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                text_quantity.Text =  reader["Quantity"].ToString();
                label_itemID.Text = reader["ItemID"].ToString();
            }

            connection.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error " + ex);
        }
    }


    // Button Load/Refresh the table
    private void btn_loadTable_Click(object sender, EventArgs e)
    {
        try
        {
            connection.Open();
            OleDbCommand command = new OleDbCommand();
            command.Connection = connection;
            string query = "select * from Inventory";
            command.CommandText = query;

            int itemCount = 0;

            OleDbDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                itemCount++;

                int quantity;

                if (quantity > 15)
                {

                }
            }

            // Connect Inventory table to Grid
            OleDbDataAdapter data = new OleDbDataAdapter(command);
            DataTable inventory_table = new DataTable();
            data.Fill(inventory_table);
            dataGridView_inventory.DataSource = inventory_table;


            connection.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error " + ex);
        }
    }

    // Button Update
    private void btn_update_Click(object sender, EventArgs e)
    {
        try
        {
            connection.Open();
            OleDbCommand command = new OleDbCommand();
            command.Connection = connection;
            string query = "update Inventory set Quantity='" + text_quantity.Text + "' where ItemID=" + label_itemID.Text + "";
            command.CommandText = query;

            command.ExecuteNonQuery();
            MessageBox.Show("Update Successful");
            text_quantity.Text="";
            connection.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error " + ex);
        }
    }
}
}

和

Answer 1

根据您的代码，当您获得 selected 项目的数量时，您应该在 combo_inventory_SelectedIndexChanged 方法中进行测试。

如果用户碰巧 select 数量少于 15 的文章，这只会弹出警告。

否则，如果您的意思是您想要某种自动化方式，那么您将需要以固定的时间间隔（计时器）或在应用程序工作流中的固定位置对小于 15 的数量执行查询.

至于查询，它与您已经为填充 ComboBox 所做的非常相似，但您只需将 WHERE 子句添加到 return 数量 < 15 的项目，然后你要么为每个项目弹出一个消息框，要么弹出一个显示 "faulty" 项列表的消息框。

如果您需要更具体的答案，请更新您的问题并指定您希望实施的方法（计时器或工作流）。

干杯

编辑：

根据您的意见，我整理了这个概念验证代码。它的一部分在 Program class 中，我假设您已经将其作为 Windows Forms 应用程序的一部分：

static class Program
{
    public static event EventHandler CheckInventoryEvent;

    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        System.Timers.Timer tmr = new System.Timers.Timer(300000); //Every 5 minutes
        tmr.Elapsed += Tmr_Elapsed;

        tmr.Start();


        Application.Run(new MainForm());

        tmr.Stop();
    }

    private static void Tmr_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
    {
        OnCheckInventoryEvent();
    }

    public static void OnCheckInventoryEvent()
    {
        if (CheckInventoryEvent != null)
            CheckInventoryEvent(null, EventArgs.Empty);
    }
}

解决方案的另一部分将在您向用户显示的任何表单中。

例如，假设这是 Inventory 表单（可以是您应用程序中的任何表单）：

public InventoryForm()
{
    InitializeComponent();

    Program.CheckInventoryEvent += Program_CheckInventoryEvent;

}

private void Program_CheckInventoryEvent(object sender, EventArgs e)
{
    try
    {
        connection.Open();
        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;
        string query = "select Item, Quantity from Inventory WHERE Quantity < 15";
        command.CommandText = query;

        // Find low Inventory items and display in dialog
        StringBuilder sb = new StringBuilder();
        OleDbDataReader reader = command.Execute();
        while (reader.Read())
        {
            sb.AppendLine(string.Format("{0} qty: {1}"), reader["Item"].ToString(), reader["Quantity"].ToString());
        }
        connection.Close();

        MessageBox.Show(sb.ToString(), "Low Inventory Items");
    }
    catch (Exception ex)
    {
        MessageBox.Show("Error " + ex);
    }
}

这很粗糙，仅作为 POC，所以请随意改编。

我在程序 class 中设置定时器的原因是，无论您的用户当前使用哪个 windows/GUI，定时器都会在任何情况下触发。

一个改进是将检查和随附的对话框移动到它自己的 class 这样您实际上就不会在每个表单中重复相同的代码。

我希望这能让你走上正轨。

干杯

C# with Access DB - 达到临界水平时将警报框放入库存

C# with Access DB - Put Alert Box in Inventory when critical level is reached

c#

database

oop

ms-access

inventory