Question

我有三张桌子。 Config，capability和config_capability将前两个关联起来。

配置可以有多个功能，因此config_capability可能看起来像

id | config_id | capability_id
1    1           1
2    1           2
3    2           1
4    2           2
5    2           3

我想找到具有仅某些功能的配置。

SELECT
    config.name
FROM
    config
JOIN
    config_capability AS cc
ON
    config.id = cc.config_id
JOIN
    capability
ON
    cc.capability_id = capability.id
WHERE
    config.node_count <= 4
AND cc.capability_id IN (
    SELECT id
    FROM capability
    WHERE capability.name = 'cap1'
    OR capability.name = 'cap2')
GROUP BY config.name
HAVING COUNT(cc.config_id) = 2

这个查询给了我配置1和配置2，但我只想找到功能1和2而不是3的配置

Answer 1

您可以尝试：

HAVING COUNT(cc.config_id) = 2 and max(cc.config_id)<3

Answer 2

您可以在下面重写查询，当您在联接中拥有该表时，无需使用额外的子查询

SELECT
    c.name
FROM
    config c
JOIN
    config_capability AS cc
ON
    c.id = cc.config_id
JOIN
    capability ca
ON
    cc.capability_id = ca.id
 WHERE
    config.node_count <= 4
GROUP BY c.name
 HAVING sum(ca.name NOT IN('cap1','cap2')) = 0

SQL选择仅包含特定属性的项目

2 个答案:

Demo