diff --git a/EHDownloader/Book.cs b/EHDownloader/Book.cs
index 69c2c03..5d0cbb3 100644
--- a/EHDownloader/Book.cs
+++ b/EHDownloader/Book.cs
@@ -29,33 +29,40 @@ namespace EHDownloader
         DownloadImageFailed,
     }
 
-    enum BookStates
+    enum BookStates:int
     {
         [Description("等待")]
-        Wait,
+        Wait = 0,
         //[Description("擷取頁面失敗")]
         //FetchError,
         [Description("載入首頁失敗")]
-        LoadFailed,
+        LoadFailed = -1,
         [Description("擷取標題失敗")]
-        FetchTitleFailed,
+        FetchTitleFailed = -2,
         [Description("擷取頁集合失敗")]
-        FetchPageSetFailed,
+        FetchPageSetFailed = -3,
         [Description("擷取頁連結失敗")]
-        FetchPageLinkFailed,
+        FetchPageLinkFailed = -4,
+        [Description("下載完成, 但是有些頁面出錯")]
+        DownloadFinishedButSomePageError = -5,
 
         [Description("擷取頁面完成")]
-        FetchCompleted,
-
-
-
+        FetchCompleted = 1,
         [Description("下載完成")]
-        DownloadCompleted,
-        [Description("下載完成, 但是有些頁面出錯")]
-        DownloadFinishedButSomePageError,
-        Compressed,
+        DownloadCompleted = 2,
+        [Description("下載並封裝完成")]
+        Compressed = 3,
     }
 
+    static class BookStateHelper
+    {
+        static public bool IsCompleted(this BookStates? state)
+        {
+            return state.HasValue && ((int)state.Value) >= (int)BookStates.Compressed;
+        }
+    }
+
+
     class Book
     {
         private const string PageSetXPath = @"//table[@class='ptb']//a";
@@ -74,7 +81,7 @@ namespace EHDownloader
 
         public List<Page> Pages { get; private set; }
 
-        public int PageCount => Pages.Count;
+        public int PageCount => Pages?.Count ?? 0;
 
         public BookStates State { get; set; } = BookStates.Wait;
 
diff --git a/EHDownloader/DbContext.cs b/EHDownloader/DbContext.cs
index 945ef00..7853645 100644
--- a/EHDownloader/DbContext.cs
+++ b/EHDownloader/DbContext.cs
@@ -99,6 +99,29 @@ namespace EHDownloader
             }
         }
 
+        public bool BookIsCompleted(string url)
+        {
+            using (var cn = new SQLiteConnection(Settings.GetConnectString()))
+            {
+                var query =
+                    "select State from Book where Url=(@url)";
+                int? state = cn.Query<int?>(query, new { url }).FirstOrDefault();
+                return ((BookStates?)state).IsCompleted();
+            }
+        }
+
+        // null: book not exists
+        public BookStates? QueryBookState(string url)
+        {
+            using (var cn = new SQLiteConnection(Settings.GetConnectString()))
+            {
+                var query =
+                    "select State from Book where Url=(@url)";
+                int? state = cn.Query<int?>(query, new { url }).FirstOrDefault();
+                return (BookStates)state;
+            }
+        }
+
         public void InsertBook(Book book)
         {
             using (var cn = new SQLiteConnection(Settings.GetConnectString()))
@@ -109,12 +132,13 @@ namespace EHDownloader
             }
         }
 
-        public void updateBookStatus(Book book)
+        public void UpdateBook(Book book)
         {
             using (var cn = new SQLiteConnection(Settings.GetConnectString()))
             {
                 var updateScript =
-                    "UPDATE Book SET (State=@State) WHERE Url=@Url";
+                    "UPDATE Book SET Title=@Title,PageCount=@PageCount,DownloadDateTime=@DownloadDateTime,State=@State,Path=@Path " +
+                    "WHERE Url=@Url";
                 cn.Execute(updateScript, book);
             }
         }
diff --git a/EHDownloader/Form1.cs b/EHDownloader/Form1.cs
index 8ecb9ca..048988f 100644
--- a/EHDownloader/Form1.cs
+++ b/EHDownloader/Form1.cs
@@ -106,18 +106,32 @@ namespace EHDownloader
         {
             if (!isEhUrl(url)) return;
             if (lv_Tasks.Items.ContainsKey(url)) return;
-            if (_dbContext.BookIsExists(url)) return;
-            ListViewItem lvi = new ListViewItem(url) { Name = url };
-            lvi.SubItems.Add("Wait");
+            // if (_dbContext.BookIsExists(url)) return;
+            await newTask(url);
+        }
 
+        private async Task newTask(string url)
+        {
+            BookStates? newBookState = _dbContext.QueryBookState(url);
+            if (newBookState.IsCompleted())
+            {
+                // 已完成
+                return;
+            }
             Book book = new Book(url, _folder);
+            if (!newBookState.HasValue)
+                _dbContext.InsertBook(book);
+            else
+                _dbContext.UpdateBook(book);
+            
+
+        ListViewItem lvi = new ListViewItem(url) { Name = url };
+            lvi.SubItems.Add("Wait");
             lvi.Text = url;
             lvi.Tag = book;
 
             lv_Tasks.Items.Add(lvi);
             await TryStartTask(lvi);
-
-
         }
 
         private async Task TryStartTask()
@@ -140,14 +154,16 @@ namespace EHDownloader
                     {
                         case BookStates.Wait:
                             await book.FetchAsync();
+                            _dbContext.UpdateBook(book);
                             break;
                         case BookStates.FetchCompleted:
                             await book.DownloadBookAsync(new Progress<DownloadProgressInfo>(
                                 (info) => lvi.SubItems[1].Text = $"下載中 {info.PageNumber}/{info.PageCount}"));
+                            _dbContext.UpdateBook(book);
                             break;
                         case BookStates.DownloadCompleted:
                             await book.CompressAsync();
-                            _dbContext.InsertBook(book);
+                            _dbContext.UpdateBook(book);
                             goto default;
                         case BookStates.Compressed:
                         case BookStates.LoadFailed: