加入两个表并显示列的不同列表

Question

我有三个表。

1. 考生

技能

CandidateToSkillMap

个

候选和技能表被映射在CandidateToSkillMap表。在那个candidate_id和skill_id是外键。

我怎样才能跟随他们的输出？

假设我需要显示candidate_id的计算机技能= 1

计算机技能 -

• 的MS Word（x）的
• 的MS Excel（x）的
• MS油漆（ ）

它应该显示所有可用计算机技能的清晰列表，并且应该在前面有一个复选框。将检查具体的候选人是否具有该技能。

编辑 -

我有查询数据库，并加载数据到阵列 -

$ candidate_profile_computer_skills

此阵给所有的计算机技能

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 

$候选人_profile_skills_map

返回此Array技能和CandidateToSkillMap与LEFT JOIN特定候选人（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

联接会做：

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 

如果加入右侧因此c.candidate_id将不会为空，那么这意味着该人拥有该技能，并且您将其标记为 - 不。在列“candidate_id”

Answer 2

你可以使用这个

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 

这将返回所有行从技能表，你可以做一个空检查，以确定是否相关候选人具备该行的技能。

下面是一些伪：

for($row in $result) { 
    Skill name: $row["skill_name"] 
    Has skill?: $row["candidate_id"] != null ? "Yes" : "No" 
} 

Answer 4

你可以试试这个

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

Answer 5

试着这么做

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) 

上面的查询使用LEFT OUTER JOIN加入skills和candidatestoskillmap包括所有的技能表中的行。这将确保在candidatestoskillmap表中不匹配的行被包含为空值。

select部分然后查找这些值并为其指定true/false。

Where部分过滤技能类型和候选人的ID。