如何根据属性表填充布尔列？

Posted 2023-02-16

【中文标题】如何根据属性表填充布尔列？

【英文标题】：How do you populate boolean columns based on a table of properties?

【发布时间】：2021-03-08 22:13:01

【问题描述】：

我有一个名为 Product 的表，其中包含一个产品标识号和一个与该产品标识号关联的 ID。

pin id
11 10
12 11
13 12

我还有一个带有 id 和 property_id 的属性表

id property_id
10, 108
11, 109
12, 200

108 指属性 isNew，109 指属性 isPremium，200 指属性 isExclusive。

有了这些，我想创建这个临时表：

pin id isNew isPremium isExclusive
11 10 1 0 0
12 11 0 1 0
13 12 0 0 1

我该怎么做？您可以轻松地创建一个临时表，但我不确定如何映射这些值。

【参考方案1】：

您可以使用 PIVOT 函数来获得您想要的结果。

DECLARE @product table(pin int, id int)
DECLARE @property table(id int, property_id int)

insert into @product
values 
(11 ,10),
(12 ,11),
(13 ,12);

insert into @property
values
(10, 108),
(11, 109),
(12, 200);

SELECT pvt.pin, pvt.product_id, [108] as is_new,[109] as is_premium, [200] as is_exclusive  
FROM 
(SELECT p.pin, p.id, pr.id as product_id, pr.property_id
FROM @Product as p
INNER JOIN @Property as pr
ON pr.id = p.id) as t
PIVOT
(
COUNT(t.id)
for t.Property_Id in ([108],[109],[200])
) as pvt

+-----+------------+--------+------------+--------------+
| pin | product_id | is_new | is_premium | is_exclusive |
+-----+------------+--------+------------+--------------+
|  11 |         10 |      1 |          0 |            0 |
|  12 |         11 |      0 |          1 |            0 |
|  13 |         12 |      0 |          0 |            1 |
+-----+------------+--------+------------+--------------+

【参考方案2】：

你可以做条件聚合：

select pt.pin, pt.id,
    max(case when py.property_id = 108 then 1 else 0 end) as is_new,
    max(case when py.property_id = 109 then 1 else 0 end) as is_premium,
    max(case when py.property_id = 200 then 1 else 0 end) as is_exclusive
from product pt
inner join property py on py.id = pt.id
group by pt.pin, pt.id

这假设每个产品可能有多个属性 - 与您的示例数据中显示的不同。如果不是这种情况，则不需要聚合：

select pt.pin, pt.id,
    case when py.property_id = 108 then 1 else 0 end as is_new,
    case when py.property_id = 109 then 1 else 0 end as is_premium,
    case when py.property_id = 200 then 1 else 0 end as is_exclusive
from product pt
inner join property py on py.id = pt.id