AI 提問 例5, Copilot:
給我 C# .Net 8.0 的程式, 包含ImportBinary(), ExportBinary()函數, 經由以下 class CRecord, MySql 的 table tlab3, 以 Binary 的格式, 若碰到 varchar 格式的欄位, 以最大 255 bytes 存放, 第1個byte 存放實際欄位資料的 bytes 個數,  匯入或匯出 MySql 的 table tlab3 的資料, 為 Binary 檔案. 

CREATE TABLE `tlab3` (
  `fpk1` int NOT NULL,
  `fsku` varchar(16) NOT NULL,
  `fname` varchar(64) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci DEFAULT NULL,
  `fprice` decimal(13,2) NOT NULL,
  `fqty` int NOT NULL,
  `famount` decimal(13,2) NOT NULL,
  `fcreate_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `fupdate_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`fpk1`)
  UNIQUE KEY `fpk1_UNIQUE` (`fpk1`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

public class CRecord
{
	public int PK1  = 0;
	public string SKU = string.Empty;
	public string? Name = null;
	public decimal Price = 0;
	public int Qty = 0;
	public decimal Amount = 0;
	public DateTime CreateTime = DateTime.MinValue;
	public DateTime LastUpdateTime = DateTime.MinValue;
}

以下是 C# .NET 8.0 的程式碼，包含 `ImportBinary()` 和 `ExportBinary()` 函數，能以 Binary 格式匯入和匯出 `tlab3` 表格資料，並根據你的需求處理 `varchar` 欄位的格式（最多 255 bytes，且第 1 個 byte 存放資料的實際大小）：

### **程式碼**
```csharp
using System;
using System.Collections.Generic;
using System.IO;
using MySql.Data.MySqlClient;

public class DatabaseHandler
{
    private string connectionString = "Server=localhost;Database=your_database;User ID=your_user;Password=your_password;";

    // 匯出 Binary
    public void ExportBinary(string filePath)
    {
        string query = "SELECT * FROM tlab3";
        using var connection = new MySqlConnection(connectionString);
        using var command = new MySqlCommand(query, connection);
        connection.Open();
        using var reader = command.ExecuteReader();
        using var writer = new BinaryWriter(File.Open(filePath, FileMode.Create));

        while (reader.Read())
        {
            // PK1
            writer.Write(reader.GetInt32("fpk1"));

            // SKU (varchar)
            WriteVarchar(writer, reader.GetString("fsku"), 16);

            // Name (nullable varchar)
            string? name = reader.IsDBNull("fname") ? null : reader.GetString("fname");
            WriteVarchar(writer, name, 64);

            // Price
            writer.Write(reader.GetDecimal("fprice"));

            // Qty
            writer.Write(reader.GetInt32("fqty"));

            // Amount
            writer.Write(reader.GetDecimal("famount"));

            // CreateTime
            writer.Write(reader.GetDateTime("fcreate_time").ToBinary());

            // LastUpdateTime
            writer.Write(reader.GetDateTime("fupdate_time").ToBinary());
        }
    }

    private void WriteVarchar(BinaryWriter writer, string? value, int maxBytes)
    {
        byte[] data = value == null ? Array.Empty<byte>() : System.Text.Encoding.UTF8.GetBytes(value);
        byte size = (byte)Math.Min(data.Length, maxBytes);
        writer.Write(size);
        writer.Write(data, 0, size);

        // Fill remaining bytes with padding if necessary
        for (int i = size; i < maxBytes; i++)
        {
            writer.Write((byte)0);
        }
    }

    // 匯入 Binary
    public void ImportBinary(string filePath)
    {
        using var connection = new MySqlConnection(connectionString);
        connection.Open();
        using var transaction = connection.BeginTransaction();

        try
        {
            using var reader = new BinaryReader(File.Open(filePath, FileMode.Open));

            while (reader.BaseStream.Position < reader.BaseStream.Length)
            {
                // PK1
                int pk1 = reader.ReadInt32();

                // SKU (varchar)
                string sku = ReadVarchar(reader, 16);

                // Name (nullable varchar)
                string? name = ReadVarchar(reader, 64);

                // Price
                decimal price = reader.ReadDecimal();

                // Qty
                int qty = reader.ReadInt32();

                // Amount
                decimal amount = reader.ReadDecimal();

                // CreateTime
                DateTime createTime = DateTime.FromBinary(reader.ReadInt64());

                // LastUpdateTime
                DateTime lastUpdateTime = DateTime.FromBinary(reader.ReadInt64());

                string query = @"INSERT INTO tlab3 (fpk1, fsku, fname, fprice, fqty, famount, fcreate_time, fupdate_time) 
                                VALUES (@PK1, @SKU, @Name, @Price, @Qty, @Amount, @CreateTime, @LastUpdateTime) 
                                ON DUPLICATE KEY UPDATE 
                                fsku = @SKU, fname = @Name, fprice = @Price, fqty = @Qty, famount = @Amount, 
                                fcreate_time = @CreateTime, fupdate_time = @LastUpdateTime";
                using var command = new MySqlCommand(query, connection, transaction);
                command.Parameters.AddWithValue("@PK1", pk1);
                command.Parameters.AddWithValue("@SKU", sku);
                command.Parameters.AddWithValue("@Name", name ?? (object)DBNull.Value);
                command.Parameters.AddWithValue("@Price", price);
                command.Parameters.AddWithValue("@Qty", qty);
                command.Parameters.AddWithValue("@Amount", amount);
                command.Parameters.AddWithValue("@CreateTime", createTime);
                command.Parameters.AddWithValue("@LastUpdateTime", lastUpdateTime);
                command.ExecuteNonQuery();
            }

            transaction.Commit();
        }
        catch (Exception ex)
        {
            transaction.Rollback();
            Console.WriteLine($"匯入失敗: {ex.Message}");
            throw;
        }
    }

    private string ReadVarchar(BinaryReader reader, int maxBytes)
    {
        byte size = reader.ReadByte();
        byte[] data = reader.ReadBytes(size);
        reader.BaseStream.Seek(maxBytes - size, SeekOrigin.Current); // 跳過填充位元
        return System.Text.Encoding.UTF8.GetString(data);
    }
}

public class CRecord
{
    public int PK1 { get; set; }
    public string SKU { get; set; } = string.Empty;
    public string? Name { get; set; } = null;
    public decimal Price { get; set; }
    public int Qty { get; set; }
    public decimal Amount { get; set; }
    public DateTime CreateTime { get; set; } = DateTime.MinValue;
    public DateTime LastUpdateTime { get; set; } = DateTime.MinValue;
}

public class Program
{
    public static void Main()
    {
        var dbHandler = new DatabaseHandler();

        // 匯出 Binary
        dbHandler.ExportBinary("tlab3_export.bin");
        Console.WriteLine("資料已匯出至 Binary 檔案");

        // 匯入 Binary
        dbHandler.ImportBinary("tlab3_import.bin");
        Console.WriteLine("資料已成功匯入");
    }
}
```

### **程式說明**
1. **`ExportBinary()` 函數**：
   - 將表格中的資料轉換成 Binary 格式，使用 `BinaryWriter` 寫入。
   - 對 `varchar` 欄位，將資料長度放入第 1 個 byte，最多存 255 bytes，並填充不足的空間。

2. **`ImportBinary()` 函數**：
   - 讀取 Binary 資料檔案並插入或更新到 `tlab3` 表格。
   - 使用 `BinaryReader` 並根據 `varchar` 的存放邏輯解碼。

3. **例外處理**：
   - 匯入過程中使用交易 (`Transaction`) 確保資料完整性。

4. **使用注意**：
   - 確保 Binary 檔案格式和表格結構保持一致。
   - 調整 `connectionString` 為你的資料庫設定。

如果還有其他需求或需要優化此邏輯，隨時告訴我！ 😊