Question

SELECT SQL_CALC_FOUND_ROWS o . * , titles.title AS title, categories.category AS category,

images.image AS image, urls.url AS url, descriptions.description AS description,

from_sites.from_site AS from_site, prices.price AS price

FROM oglasi AS o

LEFT JOIN titles ON o.title_id = titles.title_id

LEFT JOIN categories ON o.category_id = categories.category_id

LEFT JOIN images ON o.image_id = images.image_id

LEFT JOIN urls ON o.url_id = urls.url_id

LEFT JOIN descriptions ON o.description_id = descriptions.description_id

LEFT JOIN from_sites ON o.from_site_id = from_sites.from_site_id

LEFT JOIN prices ON o.price_id = prices.price_id

WHERE categories.category_id = "28"

OR categories.category_id = "29"

OR categories.category_id = "30"

OR categories.category_id = "31"

OR categories.category_id = "32"

OR categories.category_id = "33"

OR categories.category_id = "34"

OR categories.category_id = "35"

AND from_sites.from_site_id =7

ORDER BY o.izdvojen, titles.title ASC

这里唯一的问题是忽略AND from_sites.from_site_id = 7。所以它列出了所有站点的所有子类。但是，当我只使用一个category_id和from_site_id尝试同样的查询时，它就会起作用。

有人可以告诉我这里有什么问题吗？

Answer 1

您需要使用括号明确告诉MySQL首先计算哪些子句。

试试这个：

WHERE (categories.category_id = "28"
OR categories.category_id = "29"
OR categories.category_id = "30"
OR categories.category_id = "31"
OR categories.category_id = "32"
OR categories.category_id = "33"
OR categories.category_id = "34"
OR categories.category_id = "35")
AND from_sites.from_site_id =7

或类似的东西，如果那不完全是你的意思。

Answer 2

尝试使用括号来指示如何评估逻辑运算。

如果你想要任何列出的类别中的东西，除此之外，是from_site_id = 7，那么你的where部分应如下所示：

WHERE (
      categories.category_id = "28"
      OR categories.category_id = "29"
      OR categories.category_id = "30"
      OR categories.category_id = "31"
      OR categories.category_id = "32"
      OR categories.category_id = "33"
      OR categories.category_id = "34"
      OR categories.category_id = "35"
      )
      AND from_sites.from_site_id =7

您当前的查询是返回所有行，其中category_id = 28-34 OR来自类别35且来自SiteID = 7（因此除了categoryID 35之外，所有行都会忽略fromSiteID条件。）

Answer 3

原始查询中似乎不需要很多东西。我可以建议一个简化版本吗？

SELECT title, category, image, url, description, from_site, price
FROM oglasi
LEFT JOIN titles USING (title_id)
LEFT JOIN categories USING (category_id)
LEFT JOIN images USING (image_id)
LEFT JOIN urls USING (url_id)
LEFT JOIN descriptions USING (description_id)
LEFT JOIN from_sites USING (from_site_id)
LEFT JOIN prices USING (price_id)
WHERE category_id IN (28,29,30,31,32,33,34,35) AND from_site_id =7
ORDER BY izdvojen, title

Mysql查询返回所有行。为什么？

3 个答案: