简单的联接查询协助

Question

I'd like some assistance in fixing this query. This problem is fairly simple but I'm just not able to solve it. Let me explain the background on what it currently does, and then what I need to integrate.

First, here are my current tables.

candidates table

the candidates table lists all job candidates.

candidates
-----------
id
hash
first_name
last_name

here is a dump of the candidates table:

id  hash                              first_name  last_name  
 1  092ee63c6698851ba72183388bff1b3b  Jonathan    Kushner    
 2  2d234affe1d08c3394cd499f297d7380  Dustin      Kushner   

documents table

the documents table lists all documents in the system

documents
----------
id
hash
title
source_file

here is a dump of the documents table:

id  hash             title       
 1  436etgfgdggdd    Associate Sales Resume
 2  54645655gggdgdg  Senior Officer Cover Letter
 3  ffsafsdsfdfdssf  Customer Service Resume

jobs table

the jobs table lists all jobs in the system

jobs
----------
id
hash
title

here's a dump of the jobs table:

id  hash             title       
 1  asfsfafafafdf    Associate Sales Position
 2  fddfd7sd7sd7sd7  Senior Officer Position
 3  f9df89df8sd89sd  Customer Service Position

candidates_jobs table

the candidates_jobs table connects candidates to a job

candidates_jobs
----------
id
hash
candidate_id
job_id

here's a dump of the candidates_jobs table:

id  hash                             job_id   candidate_id
 1  89efaed413163be4557133266ce295b4 1        1  
 2  afsdfdssdfsdfsdfsdfsdfsdfsdfsdfd 1        2
 3  df08dfs08sd80sdf80sdf80sd8sd8sd8 1        3

candidates_jobs_documents

the candidates_jobs_documents table connects documents to a candidate based on a job.

candidates_jobs_documents
----------
id  hash                             job_id   candidate_id  document_id
 1  saasdfasdasdasdasdasdasdasdasdas 1        1             1  
 2  dfasasasasasasasasdddsdasdasdasd 1        2             2
 3  sdfsdfsdsdsdfadfsssssssddssdsdfd 1        3             3

OK. Now let me show you my current query:

    SELECT        
      `users`.`first_name`,
      `users`.`last_name`,
      `documents`.`title`
    FROM
      `documents` 
      LEFT JOIN `candidates_jobs_documents` 
        ON `candidates_jobs_documents`.`document_id` = `documents`.`id` 
      LEFT JOIN `jobs` 
        ON `jobs`.`id` = `candidates_jobs_documents`.`job_id` 
      LEFT JOIN `candidates`
        ON candidates.id = candidates_jobs_documents.candidate_id 
      LEFT JOIN `candidates_jobs` 
        ON `candidates_jobs`.`candidates_id` = `candidates`.`id` 
    ORDER BY `candidates`.`last_name` ASC

I think I need to use an INNER JOIN on the candidates_jobs_documents table based on job.id and candidate.id but I cant figure out how to handle it with the query. also, i dont know what to use for my WHERE clause.

The query isn't right. I need to grab the documents for a specific candidate based on the job. As you are aware, the documents are pinned to a candidates job, enabling the candidates to upload documents for any job and having that document as the document for that specific job.

Any help would be appreciated.

Answer 1

SELECT candidates.first_name, candidates.last_name, documents.title
FROM candidates, documents, candidates_jobs_documents
WHERE candidates.id = candidates_jobs_id.candidate_id AND 
documents.id = candidates_jobs_documents.document_id
ORDER BY candidates.last_name ASC;

Not sure if this is what you need, but maybe. I'm a little confused by candidates_jobs_documents table... maybe you really want candidates_jobs.id in there instead of candidate.id and job_id?

Answer 2

Example of listing all documents created by Jonathan Kushner applying for Associate Sales Position.

SELECT        
`users`.`first_name`,
`users`.`last_name`,
`docs`.`title`
FROM
`candidates` as `users`
INNER JOIN (
  `candidates_jobs_documents` AS cjd
  INNER JOIN `jobs` AS j ON (cjd.`job_id` = j.id)
  INNER JOIN `documents` AS `docs` ON (cjd.`document_id` = docs.id)
) ON (`users`.id = cjd.`candidate_id`)
WHERE
j.title = 'Associate Sales Position'
AND users.first_name = 'Jonathan'
AND users.last_name = 'Kushner'

Here is working code preview at SQL Fiddle: http://sqlfiddle.com/#!9/9b16c/1