Question

UPDATE qn_answers
SET `GRADE` = -100
WHERE `QSN_ID` IN (SELECT q.`ID` FROM `questions` q
LEFT JOIN qn_answers qa ON q.`ID` = qa.`QSN_ID`
WHERE q.`QSN_TYPE_ID` = 3 AND qa.`ISCORRECT` = 0 AND qa.`GRADE` = 0);

我正在尝试根据联接表中的结果更新列，但它给出错误：1093

Answer 1

我想您想在这里加入更新，而没有子查询：

UPDATE qn_answers qa
INNER JOIN questions q
    ON qa.QSN_ID = q.ID
SET GRADE = -100
WHERE
    q.QSN_TYPE_ID = 3 AND
    qa.ISCORRECT = 0  AND
    qa.GRADE = 0;

该错误消息与您将目标表qn_answers用作联接的一部分有关。您不能直接在MySQL更新中执行此操作。

Answer 2

使用join update

UPDATE qn_answers a
join 
(SELECT q.`ID` FROM `questions` q
LEFT JOIN qn_answers qa ON q.`ID` = qa.`QSN_ID`
WHERE q.`QSN_TYPE_ID` = 3 AND qa.`ISCORRECT` = 0 AND qa.`GRADE` = 0
) b on a.`QSN_ID`=b.`ID`
SET `GRADE` = -100

Answer 3

我认为标准更新也可以在这里使用。试试这个：

UPDATE qa
SET `GRADE` = -100
FROM 
`questions` q
LEFT JOIN
`qn_answers` qa
ON
q.`ID` = qa.`QSN_ID`
WHERE q.`QSN_TYPE_ID` = 3 AND qa.`ISCORRECT` = 0 AND qa.`GRADE` = 0;

无法更新以更新表，因为它在子查询的from子句中使用

3 个答案: