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点击一个分类，把当前分类及其所有子分类的所有产品列出来

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Jun 23, 2016 pm 01:54 PM

productClassificationClick

上面是分类表，产品表就是关联分类表的 cate_id ,确定产品所属的分类

现在我想要的效果是点击一个分类，把当前分类及其所有子分类的所有产品列出来

请大神指教

想的头都破了，递归？还是？怎么弄呢？

回复讨论(解决方案)

点击了分类，于是就知道了分类号
查询数据库，凡是父类号为这个分类号的就是他的子分类了

我不是要子分类我是要所有子分类下面的产品

奇怪了，有了子分类号，还愁子分类下面的产品吗？

不知道你数据量大不大
小企业站的话，得到父分类ID后，查到所有子分类ID，然后合并到一起：2,5,6,7,8这种
再到产品表sql语句用in关键字查出来，怎么用，搜一下吧...
不清楚in能不能用到索引？

如果数据量比较大，就用冗余换效率
给分类表加一个floor字段，父分类就写0,1级子分类就写1，2级子分类写2。。。
假设你有3层分类，那么在产品表加3个字段，cate，cate1，cate2
产品属于哪个子分类，就把从父到2级子 3个字段都填满
筛选时根据传入的cateid，先查出这个分类的floor，然后查出他的所有上级分类id
剩下就是把所有得到的id作为条件筛选了
这里有个关键，要建一个BTREE索引，以cate到cateN的顺序都包括进来
同数据量方法2要快很多，但他的缺点是子分类移动时还要改产品表

奇怪了，有了子分类号，还愁子分类下面的产品吗？

这里还涉及到子分类的子分类是所有后代分类，所以我最先想到的就是递归

如果单单是一层子分类当然好办了，可是无限极分类，子分类层数个数都未知

我想到了一个方案了

我用的是无限极分类，子分类层次不一定的，子分类下面可能还有子分类，所以我最先想到的是递归，后来觉得要从数据库设计入手，就在分类表加了一个路径字段

如果你一开始是全部取出的话，那么就不存在“点击一个分类，把当前分类及其所有子分类的所有产品列出来”这么一说了
既然是点击才出来，那自然是出来的是一级子分类，再点再出。这样才是统一的风格

就是你一次性全取出来，也是按父分类指示的一级一级的读

不需要递归啊，你可以到上面一个表里“层次结构”那个字段里面找所点击分类的分类号，凡是有的都是子孙后代分类了。
比如说点击的分类，id号为18，就可以用cate_path like "%18-%" or cate_path like "%-18%"来筛选。

无限级这么关键的词你居然没说！

我觉得思路还是4楼的第二种方法，把欲查询的cateid的所有父分类id也都折腾出来，合并到一起去查
用 , 或者 - 应该都可以吧
产品的cateid字段保存这样的格式：1,5,8,21 是从1级分类到N级分类
如果想查cateid=8的所有产品，那先找出5和1这2个上级分类，生成字符串1,5,8
然后查询语句用 cateid like '$cateid %'，当然这个字段单独加个索引

补充下

如果想查cateid=8的所有产品，那先找出5和1这2个上级分类，生成字符串1,5,8

这一步的字符串可以写在数据库中，也可以把所有分类id对应的查询字符串缓存起来，实际运行时间可以跳过了^ ^

我觉得你的筛选方式会出问题的。如果是id为8的呢？"%8%"这样的表达式会把18或者81、82等等都包含进去的。

这个方法再把表达式改一下就好了啊。如果id为0的也可能被点击到的话，最后in里面除了搜索出来的之外，就得多包含一个当前点击的id自己。否则都不需要加别的了，因为只有0才会前后都不带“-”出现。

用-还是用,没有区别啊，而且也不需要查找父分类。

这个简单。就一直查询下去。

由主分类ID查询出子分类，又从子分类ID查询出第三级，又从第三级ID查询出第四级……

当然，你的服务器能经得起这样折腾才行。

不管你是不是无限级，都是这样的查询。没有捷径可走。

他有一个cate_path字段啊，不需要这样的。

这个方法再把表达式改一下就好了啊。如果id为0的也可能被点击到的话，最后in里面除了搜索出来的之外，就得多包含一个当前点击的id自己。否则都不需要加别的了，因为只有0才会前后都不带“-”出现。

兄台想的果然周全 180 也包含18，确实是要加杠杠

刚在公司没时间细看
你们讨论的是在分类上加path，然后查询产品的sql语句用in？
无限级分类用in那效率会不会...in一大堆ID
还好in可以用到索引，不知道mysql有没有为in排序，否则索引树要从头到底遍历一次，然后复杂度还要乘以id的个数

我在4楼和10楼说的都是加速查询的方案
只是实现的话怎么都有办法
获得cateid后从内存缓存中（编辑分类时一次性生成）用php的变量hash读取他的分类路径，这一步几乎不耗时间
然后直接用路径字符串借助索引树一次性定位到全部数据集，速度很快

很抱歉天气热有点浮躁，如果有错误请指正

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