mysql查询问题 - 嵌套和/或语句

Question

我有这个运行良好的查询:

SELECT count(distinct p.products_id) as total 
FROM (products p 
        LEFT JOIN manufacturers m 
        USING(manufacturers_id), products_description pd, 
              categories c, products_to_categories p2c ) 
LEFT JOIN meta_tags_products_description mtpd 
          ON mtpd.products_id= p2c.products_id 
          AND mtpd.language_id = 1 
WHERE (p.products_status = 1 AND p.products_id = pd.products_id 
       AND pd.language_id = 1 AND p.products_id = p2c.products_id 
       AND p2c.categories_id = c.categories_id 
       AND (
            (pd.products_name LIKE '%3220%' 
             OR p.products_model LIKE '%3220%' 
             OR m.manufacturers_name LIKE '%3220%' 
             OR (mtpd.metatags_keywords LIKE '%3220%' 
                 AND  mtpd.metatags_keywords !='') 
             OR 
             (mtpd.metatags_description LIKE '%3220%' 
              AND   mtpd.metatags_description !='') 
             OR 
              pd.products_description LIKE '%3220%'
            ) 
           ) 
      )

但我想要搜索那些WHERE子句,或者,如示例中给出一个数字关键字值,只需将其添加到上一个查询中即可搜索产品ID:

 OR (p.products_id=3220)

但由于某种原因,添加冻结了mysql服务器.它只是继续执行查询,它永远不会结束.我必须手动重启服务器.我做错了什么？

Answer 1

当你将OR添加到最后(假设你在最后一个paren之后添加它)时,你正在创建一个笛卡尔连接,因为你使你在WHERE子句(p.products_id = pd.products_id,p.products_id = p2c.products_id和p2c.categories_id = c.categories_id)中放置的JOIN条件无效.另外,为什么要将初始表(产品,制造商,products_description,categories,products_to_categories)放在括号内？相反,尝试更像这样的东西:

SELECT count(distinct p.products_id) as total 
FROM products p 
LEFT JOIN manufacturers m USING(manufacturers_id)
LEFT JOIN products_description pd using products_id
LEFT JOIN categories c USING (categories_id)
LEFT JOIN products_to_categories p2c USING (products_id)
LEFT JOIN meta_tags_products_description mtpd 
          ON mtpd.products_id= p2c.products_id 
          AND mtpd.language_id = 1 
WHERE (p.products_status = 1  
       AND pd.language_id = 1  
       AND (
            (pd.products_name LIKE '%3220%' 
             OR p.products_model LIKE '%3220%' 
             OR m.manufacturers_name LIKE '%3220%' 
             OR (mtpd.metatags_keywords LIKE '%3220%' 
                 AND  mtpd.metatags_keywords !='') 
             OR 
             (mtpd.metatags_description LIKE '%3220%' 
              AND   mtpd.metatags_description !='') 
             OR 
              pd.products_description LIKE '%3220%'
            ) 
           ) 
      )
      OR (p.products_id=3220)

我不明白你的p.products_status = 1 AND pd.language_id = 1意思是什么,所以你可能需要调整它们在JOIN中的含义.