class Program
{
    static void Main()
    {
        string connString = "Host=myServerAddress;Port=myPort;Username=myUsername;Password=myPassword;Database=myDatabase";
        using (var conn = new NpgsqlConnection(connString))
        {
            conn.Open();
            // 執(zhí)行 SQL 查詢以獲取圖像數(shù)據(jù)
            string sql = "SELECT image_column FROM your_table WHERE id = @id";
            int id = 1; // 替換為你要查詢的圖像的 ID
            using (var cmd = new NpgsqlCommand(sql, conn))
            {
                cmd.Parameters.AddWithValue("@id", id);
                // 讀取圖像數(shù)據(jù)
                using (var reader = cmd.ExecuteReader(CommandBehavior.SequentialAccess))
                {
                    if (reader.Read())
                    {
                        // 獲取十六進制字符串
                        string hexString = reader.GetString(0);
                        // 將十六進制字符串轉(zhuǎn)換為字節(jié)數(shù)組
                        byte[] imageData = StringToByteArray(hexString);
                        // 創(chuàng)建圖像對象
                        using (MemoryStream ms = new MemoryStream(imageData))
                        {
                            Image image = Image.FromStream(ms);
                            // 顯示圖像
                            ShowImage(image);
                        }
                    }
                }
            }
        }
    }
    static void ShowImage(Image image)
    {
        // 創(chuàng)建一個新的窗體
        using (var form = new System.Windows.Forms.Form())
        {
            // 創(chuàng)建 PictureBox 控件
            var pictureBox = new System.Windows.Forms.PictureBox();
            pictureBox.Dock = System.Windows.Forms.DockStyle.Fill;
            pictureBox.Image = image;
            // 將 PictureBox 添加到窗體中
            form.Controls.Add(pictureBox);
            // 設(shè)置窗體大小并顯示
            form.Size = new System.Drawing.Size(image.Width, image.Height);
            form.ShowDialog();
        }
    }
    static byte[] StringToByteArray(string hex)
    {
        int NumberChars = hex.Length / 2;
        byte[] bytes = new byte[NumberChars];
        using (var sr = new StringReader(hex))
        {
            for (int i = 0; i < NumberChars; i++)
                bytes[i] = Convert.ToByte(new string(new char[2] { (char)sr.Read(), (char)sr.Read() }), 16);
        }
        return bytes;
    }
}

using Npgsql;
using System;
using System.Data;
using System.Drawing;
using System.IO;
class Program
{
    static void Main()
    {
        string connString = "Host=myServerAddress;Port=myPort;Username=myUsername;Password=myPassword;Database=myDatabase";
        using (var conn = new NpgsqlConnection(connString))
        {
            conn.Open();
            // 執(zhí)行 SQL 查詢以獲取圖像數(shù)據(jù)
            string sql = "SELECT image_column FROM your_table WHERE id = @id";
            int id = 1; // 替換為你要查詢的圖像的 ID
            using (var cmd = new NpgsqlCommand(sql, conn))
            {
                cmd.Parameters.AddWithValue("@id", id);
                // 讀取圖像數(shù)據(jù)
                using (var reader = cmd.ExecuteReader(CommandBehavior.SequentialAccess))
                {
                    if (reader.Read())
                    {
                        // 獲取圖像數(shù)據(jù)字節(jié)數(shù)組
                        byte[] imageData = (byte[])reader["image_column"];
                        // 創(chuàng)建圖像對象
                        using (MemoryStream ms = new MemoryStream(imageData))
                        {
                            Image image = Image.FromStream(ms);
                            // 顯示圖像
                            ShowImage(image);
                        }
                    }
                }
            }
        }
    }
    static void ShowImage(Image image)
    {
        // 創(chuàng)建一個新的窗體
        using (var form = new System.Windows.Forms.Form())
        {
            // 創(chuàng)建 PictureBox 控件
            var pictureBox = new System.Windows.Forms.PictureBox();
            pictureBox.Dock = System.Windows.Forms.DockStyle.Fill;
            pictureBox.Image = image;
            // 將 PictureBox 添加到窗體中
            form.Controls.Add(pictureBox);
            // 設(shè)置窗體大小并顯示
            form.Size = new System.Drawing.Size(image.Width, image.Height);
            form.ShowDialog();
        }
    }
}