Question

SELECT * FROM property
LEFT JOIN installmentagreement
ON property.PId=installmentagreement.PId
LEFT JOIN installments
ON installmentagreement.Id=installments.Id
LEFT JOIN rentagreement
ON property.PId=rentagreement.PId
WHERE property.PId=39

这是按预期工作的SELECT查询。我想删除此SELECT查询的结果。我使用了这个查询。

DELETE FROM property( SELECT * FROM property
LEFT JOIN installmentagreement
ON property.PId=installmentagreement.PId
LEFT JOIN installments
ON installmentagreement.Id=installments.Id
LEFT JOIN rentagreement
ON property.PId=rentagreement.PId
WHERE property.PId=39)

这也是。

DELETE FROM property
LEFT JOIN installmentagreement
ON property.PId=installmentagreement.PId
LEFT JOIN installments
ON installmentagreement.Id=installments.Id
LEFT JOIN rentagreement
ON property.PId=rentagreement.PId
WHERE property.PId=39

但它返回语法错误。我想将SELECT查询转换为DELETE查询。我正在使用的数据库是MySQL。如果有任何其他更好的解决方案，请建议。请帮忙！

Answer 1

为了清晰起见，我建议使用别名：

SELECT *
FROM property as p
LEFT JOIN installmentagreement as ia
ON p.PId=ia.PId
LEFT JOIN installments as i
ON ia.Id=i.Id
LEFT JOIN rentagreement as ra
ON p.PId=ra.PId
WHERE p.PId=39

然后您可以轻松转换为删除语句，如下所示：

delete p
FROM property as p
LEFT JOIN installmentagreement as ia
ON p.PId=ia.PId
LEFT JOIN installments as i
ON ia.Id=i.Id
LEFT JOIN rentagreement as ra
ON p.PId=ra.PId
WHERE p.PId=39

如果您想在删除property记录之前删除某些左连接表中的记录，您可以轻松更改delete语句中的别名：

delete ra
FROM property as p
LEFT JOIN installmentagreement as ia
ON p.PId=ia.PId
LEFT JOIN installments as i
ON ia.Id=i.Id
LEFT JOIN rentagreement as ra
ON p.PId=ra.PId
WHERE p.PId=39

Answer 2

MySQL支持在一个语句中删除多个表，但您需要指定要从中删除的表：

DELETE p, ima, i, ra
    FROM property p LEFT JOIN
         installmentagreement ima
         ON p.PId = ima.PId LEFT JOIN
         installments i
         ON ima.Id = i.Id LEFT JOIN
         rentagreement ra
         ON p.PId = ra.PId
WHERE p.PId = 39;

当然，您不必在DELETE之后包含所有四个表格，只包括您要删除的表格。

使用3个表的左连接删除所有

2 个答案: