要將C#中的Cookie同步到數據庫，可以通過以下步驟實現：

1. 首先，獲取C#中的Cookie信息。可以使用HttpCookie類來獲取Cookie的鍵值對信息。

HttpCookie cookie = Request.Cookies["cookieName"];

2. 接下來，連接到數據庫并將Cookie信息保存到數據庫中。可以使用ADO.NET或Entity Framework等技術來連接數據庫并執行插入操作。

使用ADO.NET示例代碼：

string connectionString = "Data Source=YourServer;Initial Catalog=YourDatabase;Integrated Security=True";
using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    string query = "INSERT INTO Cookies (CookieName, CookieValue) VALUES (@CookieName, @CookieValue)";
    SqlCommand command = new SqlCommand(query, connection);
    command.Parameters.AddWithValue("@CookieName", cookie.Name);
    command.Parameters.AddWithValue("@CookieValue", cookie.Value);
    command.ExecuteNonQuery();
}

使用Entity Framework示例代碼：

using (var context = new YourDbContext())
{
    context.Cookies.Add(new Cookie { Name = cookie.Name, Value = cookie.Value });
    context.SaveChanges();
}

3. 最后，確保在需要時可以從數據庫中檢索Cookie信息。可以編寫查詢語句來檢索數據庫中的Cookie信息并將其同步到C#中。

使用ADO.NET示例代碼：

using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    string query = "SELECT CookieName, CookieValue FROM Cookies WHERE CookieName = @CookieName";
    SqlCommand command = new SqlCommand(query, connection);
    command.Parameters.AddWithValue("@CookieName", "cookieName");
    using (SqlDataReader reader = command.ExecuteReader())
    {
        while (reader.Read())
        {
            HttpCookie cookie = new HttpCookie(reader["CookieName"].ToString(), reader["CookieValue"].ToString());
            Response.Cookies.Add(cookie);
        }
    }
}

使用Entity Framework示例代碼：

using (var context = new YourDbContext())
{
    var cookie = context.Cookies.Where(c => c.Name == "cookieName").FirstOrDefault();
    if (cookie != null)
    {
        HttpCookie httpCookie = new HttpCookie(cookie.Name, cookie.Value);
        Response.Cookies.Add(httpCookie);
    }
}

通過以上步驟，您可以實現將C#中的Cookie同步到數據庫中，并在需要時從數據庫中檢索Cookie信息并將其同步回C#中。