Mysql select query for getting co-workers - mysql

Question

I have a many to many relationship between some Jobs and some Workers.
Each worker has a property like age. I want to get all the Jobs and Workers that collaborate with the workers of age 22 (for example), including the workers of age 22.
For example if A and B are two workers who do the Job X and one of them is 22 years old, I want a query to return both A and B (joined with the X and its properties)
I have three tables:
Job
1 JobI
2 JobII
Workers:
A Smith 22
B John 21
C Jack 23
J-W relation
1 A
1 B
2 B
2 C
In this example I want A and B info and Job I because A is 22 years old and collaborate with B in Job I

Answer 1

Something like
Select * From Workers
join (Select Distinct WorkerID From WorkerJobs Join Workers on Worker.WorkerID = WorkerJobs.WorkerID and Worker.Age = 22) worker22 on worker22.workerid = worker.workerid
join Jobs on jobs.jobid = workerjobs.jobid
join WorkerJobs on Workerjobs.workerid = workers.workerid
and WorkerJobs.JobId = Jobs.JobID
Ie get all the jobs with a 22 year old worker, then join back to jobs and workers to get the details.
Any 22 year old with more than one job will repeat as will any job with more than one 2 year old worker though.

Answer 2

Your question is a bit confusing.. Do you want all jobs for workers of age 22 or want to return A and B? Still I will try to answer both.
Lets say in your jobs table you have job_id,worker_id,job_description.... and lets say in your worker table you have worker_id,age,other description
In order to get all the jobs and workers with age 22 run following query.
SELECT jobs.*,workers.* FROM jobs,workers WHERE jobs.worker_id = workers.worker_id AND workers.age=22;
This will return all the jobs data and workers data associated with workers with age 22.
Hope this answers your question

Answer 3

Assuming your schema looks like this:
Table workers {
id,
age,
...
}
Table jobs {
id,
worker_id,
...
}
To answer your question, you need a query with a subquery.
The inner query
select jobs.id
from jobs
left join workers on workers.id = jobs.worker_id
where age = 22
returns all the jobs, who have workers aged 22.
The outer query
select *
from jobs, workers
where jobs.worker_id = workers.id
and jobs.id in (INNER QUERY)
selects all the jobs and workers, who have a job in the inner query.
The end result:
select *
from jobs, workers
where jobs.worker_id = workers.id
and jobs.id in (select jobs.id
from jobs
left join workers on workers.id = jobs.worker_id
where age = 22)