sql - 使用 AND 和 OR 通过查询检索多行

Question

我想使用相同的 ID 检索多行。因此有了这个表“component_property”，我想根据我的 SQL 查询(检查下面)得到 2 条记录，id:8 和 9，但是当然没有检索任何东西，因为我正在检查 cp. property_id = 9102 及更高版本并检查 cp.property_id = 8801 是否同时是不可能的。

ID;type_id;name;desc;property_id,value
--------------------------------------
8;3832;"amplifier1";"";8801;"3"
8;3832;"amplifier1";"";9102;"4015"
9;3832;"amplifier2";"";8801;"3"
9;3832;"amplifier2";"";9102;"4016"

这是我目前没有检索到任何内容的查询。

SELECT c.id, c.type_id, cp.property_id, cp.value 
FROM components_component AS c 
INNER JOIN components_componentproperty AS cp 
ON c.id = cp.component_id 
WHERE 
(cp.property_id = 9102  AND cp.value IN ('4015', '4016')) 
OR
(cp.property_id = 8801  AND cp.value = '3') 
AND c.type_id = 3832

组件===>组件属性<===属性

组件

id serial NOT NULL,
type_id integer NOT NULL,
name character varying(50) NOT NULL,
description character varying(255),

组件属性

id serial NOT NULL,
component_id integer NOT NULL,
property_id integer NOT NULL,
value character varying(255),

属性

id serial NOT NULL,
code character varying(10),
preferred_name character varying(50),

我的预期结果是:

id;name
-------
8;amplifier1
9;amplifier2

Answer 1

这是一个关系除法的例子:

SELECT c.id, c.name
FROM   components_componentproperty cp1
JOIN   components_componentproperty cp2 USING (component_id)
JOIN   components_component         c   ON c.id = cp1.component_id
WHERE  cp1.property_id = 9102  AND cp1.value IN ('4015', '4016')
AND    cp2.property_id = 8801  AND cp2.value = '3'
AND    c.type_id = 3832
GROUP  BY c.id;

我们在这里汇集了一系列相关技术:

• How to filter SQL results in a has-many-through relation

检查大量属性

您可以扩展上述查询，对于一手完整的属性，这将是最快的解决方案之一。对于更大的数字，走这条路会更方便(也开始更快):

5 个属性的示例，根据需要扩展:

SELECT c.id, c.name
FROM  (
   SELECT id
   FROM  (
      SELECT component_id AS id, property_id  -- alias id just to shorten syntax
      FROM   components_componentproperty
      WHERE  property_id IN (9102, 8801, 1234, 5678, 9876)  -- expand as needed
      GROUP  BY 1,2
      ) cp1
   GROUP  BY 1
   HAVING count(*) = 5  -- match IN expression
   ) cp2
JOIN   components_component c USING (id);

内部子查询 cp1 的额外步骤只是必要的，因为您显然在 components_componentproperty 中每个 (component_id, property_id) 有多个条目.我们可以将cp1和cp2合二为一并检查

HAVING count(DISTINCT property_id) = 5

但我预计这会更昂贵，因为 count(DISTINCT col) 每行 需要一次排序操作。

对于非常长的列表，IN 是一个糟糕的选择。考虑:

• Optimizing a Postgres query with a large IN