SQL加入where和limit

Question

我想知道如何：

- Select 10 random jobs 
- Join the default jobs location name
- Join the default jobs sector name

对于每个加入表，如果作业有多个位置，我已添加_default。

我有以下数据库结构。

我遇到的问题是此查询多次返回相同的作业。

SELECT j.job_id, j.job_name, j.job_uri, j.job_image1, s.section_name as section
FROM jobs j
LEFT JOIN job_sectors js ON j.job_id = js.job_id
LEFT JOIN sectors s ON s.sector_id = js.sector_id
WHERE j.job_featured = '1'
AND j.job_status = 'ENABLED'
ORDER BY RAND()
LIMIT 10

Answer 1

您可以在子查询中选择10个作业。如果一个作业有多个扇区，那么最终会有10行以上（但仍有10个作业。）

select  *
from    (
        select  *
        from    jobs
        where   jobs.job_featured = '1'
                and jobs.status = 'ENABLED'
        order by
                rand()
        limit 10
        ) as j
left join
        job_sectors js
on      js.job_id = j.job_id
left join
        sectors s
on      s.sector_id = js.sector_id