Question

我在尝试执行此查询时遇到错误，因为MySQL意识到我正在尝试通过一组来自同一个表上的JOIN的结果删除一些记录。

如何重写查询？

DELETE FROM hr_descr2 
WHERE
    id IN (SELECT 
        a.id
    FROM
        hr_descr2 a,
        hyperreview_descr b    
    WHERE
        a.titolo = b.titolo
        AND a.recensione != b.recensione
        AND a.recensione != ''
        AND b.recensione != ''
        AND ABS(LENGTH(a.recensione) - LENGTH(b.recensione)) > 40);

我也试图以这种方式重写查询，但它不起作用：

WITH temp AS(SELECT 
        a.id
    FROM
        hr_descr2 a,
        hyperreview_descr b    
    WHERE
        a.titolo = b.titolo
        AND a.recensione != b.recensione
        AND a.recensione != ''
        AND b.recensione != ''
        AND ABS(LENGTH(a.recensione) - LENGTH(b.recensione)) > 40)
DELETE FROM hr_descr2 
WHERE
    id IN (select id from temp);

Answer 1

首先，我不认为MySQL支持CTE，因此with在语法上不正确。

我没试过，但我认为这样的事情应该有用吗？

DELETE hr_descr2 
FROM hr_descr2 a,
    hyperreview_descr b    
WHERE
    a.titolo = b.titolo
    AND a.recensione != b.recensione
    AND a.recensione != ''
    AND b.recensione != ''
    AND ABS(LENGTH(a.recensione) - LENGTH(b.recensione)) > 40);

Answer 2

而你可以使用

DELETE a FROM
    hr_descr2 a,
    hyperreview_descr b    
WHERE
    a.titolo = b.titolo
    AND a.recensione != b.recensione
    AND a.recensione != ''
    AND b.recensione != ''
    AND ABS(LENGTH(a.recensione) - LENGTH(b.recensione)) > 40

MySQL：使用同一个表从上一个查询的结果中删除

2 个答案: