数据库 SQL 不包括数据

Question

I have a problem getting data when joining 2 tables, JOB and Application .

The Job table has id, title and description, while the Application table has id, applicant and job_id.

I wanted to show the jobs that the applicant haven't applied yet

ID   TITLE               DESCRIPTION
--------------------------------------
2    web developer       some text
3    web designer        some text
4    project manager     some text

ID   applicant  job_id
-----------------------
1       28        2
2        1        2
3        1        3

So I tried this query:

select 
    job.id, job.title ,job.description 
from 
    `job` 
left join 
    `application` on `job`.`id` = `application`.`job` 
where 
    `application`.`applicant` != 28 
    or `application`.`applicant` is null

but this just returns all jobs.

Answer 1

You can use NOT IN . So, the code should be look like given blow =>

SELECT job.id, job.title ,job.description FROM JOB 
WHERE ID NOT IN (SELECT job_id FROM Application);  

Answer 2

You can use NOT EXISTS as follows:

select j.* 
 from `job` j 
where not exists
      (select 1 from `application` a 
        where j.`id` = a.`job` and a.`applicant` = 28)