Question

我有一个子查询：

SELECT INTER1.LID1 AS ILID1,INTER1.LID2 AS ILID2 FROM
(SELECT L1.ID1 AS LID1, L1.ID2 AS LID2 FROM Friend F1
INNER JOIN Likes L1
ON F1.ID1 = L1.ID1 AND F1.ID2 = L1.ID2) INTER1
LEFT JOIN Likes L2
ON (INTER1.LID1 = L2.ID2 AND INTER1.LID2 = L2.ID1)
WHERE (L2.ID1 IS NULL AND L2.ID2 IS NULL)

输出如下：

     ID1    ID2

    1641    1468
    1911    1247

现在我必须从表LIKES中删除这两行，其格式如下：

  ID1       ID2

 1689       1709
 1709       1689
 1782       1709
 1911       1247
 1247       1468
 1641       1468

我试图在SQLite中使用以下查询来完成此任务：

DELETE FROM Likes 
WHERE EXISTS 
(SELECT INTER1.LID1 AS ILID1,INTER1.LID2 AS ILID2 FROM
(SELECT L1.ID1 AS LID1, L1.ID2 AS LID2 FROM Friend F1
INNER JOIN Likes L1
ON F1.ID1 = L1.ID1 AND F1.ID2 = L1.ID2) INTER1
LEFT JOIN Likes L2
ON (INTER1.LID1 = L2.ID2 AND INTER1.LID2 = L2.ID1)
WHERE (L2.ID1 IS NULL AND L2.ID2 IS NULL));

但它没有按预期工作，它不会只删除那些行。

然后我尝试使用INNER JOIN来解决这个问题，但是与DELETE函数关联的INNER JOIN的功能并不在SQLite中。

我该怎样才能做到这一点。

请帮助

Answer 1

只需一次比较两个值：

DELETE FROM Likes
WHERE (ID1, ID2) IN (SELECT ... your original query ...);

Row values需要SQLite 3.15或更高版本。如果您使用的是早期版本，则必须在单独的步骤中使用单列主键（rowid或您声明为INTEGER PRIMARY KEY的任何内容）查找要删除的行：

DELETE FROM Likes
WHERE rowid IN (SELECT Likes.rowid
                FROM Likes
                JOIN (SELECT ... your original query ...) AS IDs
                  ON Likes.ID1 = IDs.ILID1
                 AND Likes.ID2 = IDs.ILID2);

如何从SQLite中的表中删除多行

1 个答案: