Join two tables and display distinct list of column - php

Question

I have three tables.
Candidates
Skills
CandidateToSkillMap
Candidate and Skill tables are mapped in CandidateToSkillMap table. In that candidate_id and skill_id are foreign keys.
How can i get following output with them ?
Assume i need to display Computer Skills of candidate_id = 1
Computer Skills -
MS Word (x)
MS Excel (x)
MS Paint ()
It should display distinct list of all available computer skills and there should be a check-box in-front. It will be checked if specific candidate has that skill.
EDIT -
I have query database and loaded data into arrays -
$candidate_profile_computer_skills
this array gives all the computer skills
array (size=3)
0 =>
object(Candidate\Model\CandidateProfileSkill)[317]
public 'id' => string '1' (length=1)
public 'skill_name' => string 'MS Word' (length=7)
public 'candidate_id' => null
public 'candidateprofileskill_id' => null
1 =>
object(Candidate\Model\CandidateProfileSkill)[223]
public 'id' => string '3' (length=1)
public 'skill_name' => string 'MS Excel' (length=8)
public 'candidate_id' => null
public 'candidateprofileskill_id' => null
2 =>
object(Candidate\Model\CandidateProfileSkill)[316]
public 'id' => string '6' (length=1)
public 'skill_name' => string 'MS Paint' (length=8)
public 'candidate_id' => null
public 'candidateprofileskill_id' => null
$candidate_profile_skills_map
this array returns Skills and CandidateToSkillMap with LEFT JOIN for specific candidate (candidate_id = 1)
array (size=5)
0 =>
object(Candidate\Model\CandidateProfileSkill)[321]
public 'id' => string '1' (length=1)
public 'skill_name' => string 'MS Word' (length=7)
public 'candidate_id' => string '1' (length=1)
public 'candidateprofileskill_id' => string '1' (length=1)
1 =>
object(Candidate\Model\CandidateProfileSkill)[322]
public 'id' => string '2' (length=1)
public 'skill_name' => string 'Sinhala Reading' (length=15)
public 'candidate_id' => string '1' (length=1)
public 'candidateprofileskill_id' => string '2' (length=1)
2 =>
object(Candidate\Model\CandidateProfileSkill)[323]
public 'id' => string '3' (length=1)
public 'skill_name' => string 'MS Excel' (length=8)
public 'candidate_id' => string '1' (length=1)
public 'candidateprofileskill_id' => string '3' (length=1)
3 =>
object(Candidate\Model\CandidateProfileSkill)[324]
public 'id' => string '4' (length=1)
public 'skill_name' => string 'English Reading' (length=15)
public 'candidate_id' => string '1' (length=1)
public 'candidateprofileskill_id' => string '4' (length=1)
4 =>
object(Candidate\Model\CandidateProfileSkill)[325]
public 'id' => string '4' (length=1)
public 'skill_name' => string 'English Reading' (length=15)
public 'candidate_id' => string '1' (length=1)
public 'candidateprofileskill_id' => string '4' (length=1)

Answer 1

A join will do:
SELECT
s.skill_name,
CASE WHEN c.candidate_id IS NOT NULL THEN '(X)' ELSE '()' END has_skill
FROM
skills s
LEFT JOIN CandidateToSkillMap c ON s.skill_id = c.skill_id
WHERE
c.candidate_id = 1
If it joins the right side successfully and thus c.candidate_id will be not null, then it means the person has that skill and you mark it else - don't.

Answer 2

You can just use this
Select S.SkillName, count(*) from CandidateToSkillMap CTS, Skills S where S.Id = CTS.CandidateProfileSkillId group by CV.Id having CTS.CandidateId = 1

Answer 3

SELECT * FROM [Skills] s
LEFT JOIN [CandidateToSkillMap] csm ON csm.candidateprofileskill_id = s.id
WHERE csm.candidate_id = 1
This will return all rows from the skills table, and you can do a null-check on the column "candidate_id" to ascertain whether or not the candidate in question has the skill on that row.
Here's some pseudo:
for($row in $result) {
Skill name: $row["skill_name"]
Has skill?: $row["candidate_id"] != null ? "Yes" : "No"
}

Answer 4

you can try this
select S.skill_name from CandidateToSkillMap CSM, Skills s where S.id=CSM.candidatesprofileskill_id and CSM.candidate_id=1

Answer 5

Try something like
SELECT s.skill_name, (cm.Candidate_id IS NOT NULL) AS HasSkill
FROM Skills AS s
LEFT OUTER JOIN candidateToSkillMap AS cm
ON s.id = cm.candidateprofileskill_id
WHERE s.skill_type = 'Computer Literacy'
AND (Candidate_id = 1 OR Candidate_id IS NULL)
The above query uses LEFT OUTER JOIN to join the skills and candidatestoskillmap include all the rows from skills tables. This will ensure that any rows not matched in the candidatestoskillmap table are included as null values.
The select section then looks for these values and assigns a true/false for it.
The Where section filters for the skill type and the candidate's id.