使用一个项目保存多个类别

Question

我正在建立一个网站,您可以在其中添加包含多个类别的项目.

在一个字段中存储多个类别并保持字段可搜索的最佳方法是什么？

Answer 1

您不在一个字段中存储多个类别,而是创建一个单独的表来为每个项目分配类别.与此类似:

-- create your table to store items/products
create table items
(
  id int,  -- this will be the PK
  name varchar(10)
);

insert into items values
(1, 'product1'),
(2, 'product2');

-- create your table to store categories
create table categories
(
  id int,  -- this will be the PK
  name varchar(50)
);

insert into categories values
(1, 'color'),
(3, 'material'),
(6, 'size');

-- create your join table to assign the categories to each item
-- this table will have a foreign key relationship to the items and categories table
create table items_categories
(
  item_id int,   -- both fields will be the PK
  category_id int
);

insert into items_categories values
(1,  1),
(2,  3),
(2,  6);

然后,您将通过连接表来查询数据:

select i.id itemid,
  i.name item,
  c.name category
from items i
left join items_categories ic
  on i.id = ic.item_id
left join categories c
  on ic.category_id = c.id

请参阅SQL Fiddle With Demo