我该如何修复这个MySQL DELETE查询？

Question

我有三个表，products，shops和sex。我希望product表中DELETE行的product_id行product_id表中没有等效的sex。

此外，products表中的这些行的shop_id必须等于shop_id表中的shops，其shops.shop值为{ 'www.shop.com'。

到目前为止我已经

了

DELETE FROM products USING shops WHERE
products.shop_id=shops.shop_id AND
shops.shop='www.shop.com' AND NOT EXISTS
(SELECT sex.product_id FROM sex WHERE
sex.product_id=products.product_id)

但似乎不能像我一样在子查询中引用products。 （我收到错误Unknown table 'products' in MULTI DELETE。）我如何解决错误？

Answer 1

您可以在JOIN声明中使用DELETE：

DELETE    a 
FROM      products a
JOIN      shops b ON a.shop_id = b.shop_id AND b.shop = 'www.shop.com'
LEFT JOIN sex c ON a.product_id = c.product_id
WHERE     c.product_id IS NULL

这将DELETE仅shops表中具有shop = www.shop.com的相应行的产品，但仅当该产品也 <时em> not 在sex表中有相应的行。