SQLite:使用EXCEPT从SELECT中删除结果

Question

我在SQLite DB中有两个表,Feeds和Import.我将rss feed列表中的所有附件都放入Import表中; 其中大部分都在Feeds表中.我正在尝试从"源"表中删除记录,其中磁盘不在"导入"表中,因为它们不再位于rssfeeds中并且已经下载.基本上这是我的设置:

TABLE Feeds
    id (TEXT)
    url (TEXT)
    downloaded (BIT)

TABLE Import
    id (TEXT)
    url (TEXT)

# results to delete
(SELECT id,url FROM Feeds WHERE downloaded = 1 EXCEPT SELECT id,url FROM Import)

我可能过度思考这个问题并使其变得比实际情况更复杂.

Answer 1

DELETE
  FROM Feeds
 WHERE downloaded = 1
   AND NOT EXISTS (
          SELECT *
            FROM Import b
           WHERE Feeds.id = b.id
             AND Feeds.url = b.url )