Question

我在SQLite数据库中有两个表，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)

我可能会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 )

Answer 2

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

SQLite：使用EXCEPT从SELECT中删除结果

2 个答案: