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I'm trying to make a database. It has following subset of tables
- jobs(job_id, description)
- skills (skill_id, skills)
- jobs_and_skills (job_id, skill_id)
- applicant_skill (applicant_id , skills_id)
My query must be : Find applicants who have skills required by a given jobs id
I did something like this using a series of subqueries
select DISTINCT applicant_id from applicant_skill where skill_id in (select DISTINCT skill_id from jobs_and_skill where job_id in (select job_id from jobs where description ="research"));
But here if I have a job that needs skills say A,B,C and I have candidate which has skill A only it will return that candidate also. Is there a way to find candidate that has all skills A,B,C and not return candidates with just a subset of required skills
JOIN rather than
IN. Then you can join with a subquery that counts the number of skills a job requires, and compare that with the count of skills the applicant has in common.
SELECT as.applicant_id FROM applicant_skill AS as JOIN jobs_and_skills AS js ON js.skill_id = as.skill_id JOIN jobs AS j ON j.job_id = js.job_id JOIN ( SELECT job_id, COUNT(*) AS skill_count GROUP BY job_id ) AS jsc ON j.job_id = jsc.job_id WHERE j.description = "research" GROUP BY as.applicant_id HAVING COUNT(*) = jsc.skill_count
7 Reasons Why Using SELECT * FROM TABLE in SQL Query Is a , That's a good suggestion and one of the SQL best practices I teach to junior developers, but This can make your query a little bit slow as well. Avoid using terms that indicate an uncertain diagnosis as defined by ICD-10-CM Official Guidelines for Coding and Reporting and Coding Clinic® (e.g., “likely,” “probable,” etc.) as a query response choice unless the query is either provided at the time of discharge or after discharge; then it is the responsibility of the provider to
You can prepare
subquery for jobs_and_skill before joining to
select * from applicant_skill t1 inner join (select t2.skill_id from jobs_and_skill t2 inner join skills t3 on t3.skill_id = t2.skill_id inner join jobs t4 on t4.job_id = t2.job_id where t4.description = 'research') as t on t1.skill_id = t.skill_id
Why can't clients query the DB directly using SQL?, If you keep all of that in mind, it is possible to create database-centric applications . This can be a good approach e.g. for intranet applications where you can trust� It may be the case that the query itself is not available for editing, such as a crosstab query. It may also be the case that only the field you are trying to edit is not available for editing — for example, if the field is based on an aggregate function, such as an average.
You could join
applicants with a condition that ensures that the applicant has all of job skills.
select j.*, a.* from jobs j inner join applicants a on not exists ( select 1 from job_and_skills js left join applicant_skills as on as.applicant_id = a.applicant_id and as.skill_id = js.skill_id where js.job_id = j.job_id and as.applicant_id is null ) where j.description = 'research'
The join condition uses a
not exists condition uses a left join anti-pattern that phrases as follows: there is no required skill for this job that the applicant does not own.
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- Shouldn't the second column in
- Also, don't you have a separate table for
(applicant_id, name, ...)?
- @GMB indeed I have a separate table for applicantsand also applicant_skill should have skill_id as second column