MySql获取cloumn中每种类型元素的计数 [英] MySql getting count of each type of element in a cloumn

问题描述

我有 2 个具有以下结构的表..

I have 2 tables with the following structure..

category
{
  sub_cat_id - numeric
  sub_cat_name -  varchar
  main_cat_id - varchar (2 characters)
  main_cat_name -  varchar
}

products
{
  pid - autoincrement
  pname - varchar
  category (Will be either sub_cat_id or main_cat_id)
}

产品表

pid       pname       category
1         mobile      EL
2         shoes       1
3         shirt       1 
4         TV          EL
5         mp3 player  EL

我想获取 products 表中每个类别的计数，以便我的查询返回2 对于类别 1 和3 为类别 EL

I want to get the count of each category in the products table such that my query returns 2 for category 1 and 3 for category EL

有人可以帮我吗??

推荐答案

这应该是您想要的查询:

This should be the query you're after:

SELECT category, COUNT(*) FROM products GROUP BY category;

我建议您考虑一下类别表的设计，因为这可能会给您带来麻烦.

I would recommend thinking about the design of your category table, as it might cause you difficulties in the future.

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