Form1.cs

using System;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Windows.Forms;

namespace Lab06
{
    public partial class Form1 : Form
    {
        // in-memory copy of the Books table
        private readonly DataTable dt = new DataTable();

        public Form1()
        {
            InitializeComponent();
        }

        // ───────────────────────────────────────────────────────────
        // 1.  Load database when the form starts
        // ───────────────────────────────────────────────────────────
        private void Form1_Load(object sender, EventArgs e)
        {
            try
            {
                string dbPath = Path.Combine(Application.StartupPath, "lib.accdb");
                string connStr = $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={dbPath};";
                string sqlStr = "SELECT * FROM Books";

                using (OleDbConnection conn = new OleDbConnection(connStr))
                using (OleDbDataAdapter adapter = new OleDbDataAdapter(sqlStr, conn))
                {
                    adapter.Fill(dt);
                }

                // optional grid for debugging only
                dgvBooks.DataSource = dt;
                dgvBooks.Visible = false;
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Database load error:\n{ex.Message}",
                                "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        // (still reserved – harmless to keep)
        private void dgvBooks_CellContentClick(object sender, DataGridViewCellEventArgs e) { }
        private void lstOutput_SelectedIndexChanged(object sender, EventArgs e) { }

        // ───────────────────────────────────────────────────────────
        // 2.  Show Data button – list three columns in lstOutput
        // ───────────────────────────────────────────────────────────
        private void btnShow_Click(object sender, EventArgs e)
        {
            string fmt = "{0,-30}{1,-30}{2,-30}";
            lstOutput.Items.Clear();
            lstOutput.Items.Add(string.Format(fmt, "Title", "Author", "Publisher"));
            lstOutput.Items.Add(new string('-', 90));

            foreach (DataRow row in dt.Rows)
            {
                lstOutput.Items.Add(string.Format(fmt,
                    row["Title"]?.ToString(),
                    row["Author"]?.ToString(),
                    row["Publisher"]?.ToString()));
            }
        }

        // ───────────────────────────────────────────────────────────
        // 3.  Show Status button – pop dialog, display Title/ISBN/Status
        // ───────────────────────────────────────────────────────────
        private void btnStatus_Click(object sender, EventArgs e)
        {
            // clear previous display
            txtTitle.Clear();
            txtISBN.Clear();
            txtStatus.Clear();

            using (frmSearch frm = new frmSearch())
            {
                if (frm.ShowDialog() == DialogResult.OK)
                {
                    string keyword = (frm.Result ?? string.Empty).Trim().ToUpper();
                    bool found = false;

                    foreach (DataRow row in dt.Rows)
                    {
                        // null-safe read of Title
                        string title = (row["Title"]?.ToString() ?? string.Empty).ToUpper();

                        if (title.Equals(keyword))
                        {
                            txtTitle.Text = row["Title"]?.ToString();
                            txtISBN.Text = row["ISBN"]?.ToString();
                            txtStatus.Text = row["Status"]?.ToString();
                            found = true;
                            break;
                        }
                    }

                    if (!found)
                        MessageBox.Show("No such book can be found.",
                                        "Not found", MessageBoxButtons.OK,
                                        MessageBoxIcon.Information);
                }
            }
        }
    }
}