SQLite DELETE条件，Firefox历史记录

Question

如何删除此查询的结果？，复制这些条件，但使用DELETE。

此查询返回上次访问过的网站，我会使用相同的条件删除历史记录，必须将语法转换为“DELETE FROM”并使用相同的标准请帮助..谢谢。

SELECT datetime(moz_historyvisits.visit_date/1000000, 'unixepoch') AS 'Date Visited', moz_places.title AS Title, moz_places.url AS URL, moz_places.visit_count AS Count FROM moz_historyvisits, moz_places WHERE moz_historyvisits.place_id = moz_places.id ORDER BY moz_historyvisits.visit_date ASC

或这个

SELECT datetime(moz_historyvisits.visit_date/1000000,'unixepoch') as data, moz_places.url
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0;

Answer 1

我不确定我是否完全理解你的问题，但是如果你想有选择地删除moz_places和moz_historyvisits中的相关条目，那么你应该能够使用这样的东西：

CREATE TEMPORARY VIEW delenda AS
  SELECT id FROM moz_places WHERE ($condition);

DELETE FROM moz_historyvisits WHERE place_id IN (SELECT id FROM delenda);
DELETE FROM moz_places WHERE id IN (SELECT id FROM delenda);

（将$ condition替换为您的删除标准。）

Answer 2

您可以使用WITH ..... DELETE，其中....是CTE（公用表表达式），它等同于您的查询。或者，您可以将查询用作DELETE的WHERE子句的子查询。

但是，您只需要从查询中删除足够的数据来标识要删除的行。假设该表不是WITHOUT ROWID表，那么所选表的rowid就足够了。

因此，以下方法可行： -

Solution 1 (WITH ..... DELETE)

WITH cte1 AS (SELECT moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN (SELECT rid FROM cte1);

• 请注意，datetime(moz_historyvisits.visit_date/1000000,'unixepoch') as data, moz_places.url不是必需的，因此被排除在CTE之外（可以包含它们）。

Solution 2 DELETE using SubQuery in the WHERE clause

或者，您可以使用查询（再次只是检索rowid）一个WHERE子句的子查询，如下所示： -

DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN 
    (SELECT moz_historyvisits.rowid AS rid
    FROM   moz_places, moz_historyvisits 
    WHERE  moz_places.id = moz_historyvisits.place_id
    ORDER BY 1 desc
    LIMIT 21 OFFSET 0)
;

Example Code used for Testing

以下是用于测试上述代码： -

DROP TABLE IF EXISTS moz_places;
DROP TABLE IF EXISTS moz_historyvisits;
CREATE TABLE IF NOT EXISTS moz_historyvisits (place_id INTEGER, visit_date);
CREATE TABLE IF NOT EXISTS moz_places (id INTEGER PRIMARY KEY, URL TEXT, title TEXT, visit_count INTEGER);


-- Add Some data
INSERT INTO moz_places (URL) VALUES('Rome'),('London'),('Paris'),('Sydney'),('Tokyo');
INSERT INTO moz_historyvisits VALUES(1,'2010-10-11 10:30'),(2,'2018-01-31 12:20'),(1,'2018-02-28 08:15'),(3,'2017-06-01 15:45');

-- Result 1 (show original data)
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id;


-- Result 2 (test the CTE by selecting everything extracted by the CTE)
WITH cte1 AS (SELECT datetime(moz_historyvisits.visit_date/1000000,'unixepoch') AS data, moz_places.url, moz_places.id, moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
SELECT * FROM cte1;

-- This does deleteion using WITH ..... DELETE
WITH cte1 AS (SELECT moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN (SELECT rid FROM cte1);

-- Result 43show table after deletion
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id;

-- Do alternative/equivakent deletion via subquery
DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN(SELECT moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0);

-- Result 4 show table after both deletions
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id;

Resultant Outputs

结果1 -

结果2 -

结果3 -

结果4 -

消息 -

DROP TABLE IF EXISTS moz_places
> OK
> Time: 0.356s


DROP TABLE IF EXISTS moz_historyvisits
> OK
> Time: 0.324s


CREATE TABLE IF NOT EXISTS moz_historyvisits (place_id INTEGER, visit_date)
> OK
> Time: 0.358s


CREATE TABLE IF NOT EXISTS moz_places (id INTEGER PRIMARY KEY, URL TEXT, title TEXT, visit_count INTEGER)
> OK
> Time: 0.333s


-- Add Some data
INSERT INTO moz_places (URL) VALUES('Rome'),('London'),('Paris'),('Sydney'),('Tokyo')
> Affected rows: 5
> Time: 0.265s


INSERT INTO moz_historyvisits VALUES(1,'2010-10-11 10:30'),(2,'2018-01-31 12:20'),(1,'2018-02-28 08:15'),(3,'2017-06-01 15:45')
> Affected rows: 4
> Time: 0.354s


-- Result 1 (show original data)
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id
> OK
> Time: 0s


-- Result 2 (test the CTE by selecting everything extracted by the CTE)
WITH cte1 AS (SELECT datetime(moz_historyvisits.visit_date/1000000,'unixepoch') AS data, moz_places.url, moz_places.id, moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
SELECT * FROM cte1
> OK
> Time: 0s


-- Do alternative/equivakent deletion via subquery
DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN(SELECT moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
> Affected rows: 4
> Time: 0.228s


-- Result 4 show table after both deletions
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id
> OK
> Time: 0s


-- This does deleteion using WITH ..... DELETE
WITH cte1 AS (SELECT moz_historyvisits.rowid AS rid
FROM   moz_places, moz_historyvisits 
WHERE  moz_places.id = moz_historyvisits.place_id
ORDER BY 1 desc
LIMIT 21 OFFSET 0)
DELETE FROM moz_historyvisits WHERE moz_historyvisits.rowid IN (SELECT rid FROM cte1)
> Affected rows: 0
> Time: 0s


-- Result 43show table after deletion
SELECT * FROM moz_historyvisits JOIN moz_places ON moz_historyvisits.place_id = moz_places.id
> OK
> Time: 0s