mysql - 查询 MySQL 数据库

Question

有人可以帮我在此查询中添加第三个表，其中包含疾病的风险因素。该表是 tblRiskFactors

SELECT tblDiseases.disease
FROM tblRel 
   LEFT JOIN tblDiseases ON tblRel.diseaseID = tblDiseases.diseaseID
WHERE tblRel.symptomID = '1' AND tblRel.symptomID = '2' AND tblRel.symptomID ='3'

Answer 1

SELECT  tblDiseases.disease
FROM    tblRel 
        LEFT JOIN tblDiseases 
            ON tblRel.diseaseID = tblDiseases.diseaseID
        LEFT JOIN tblRiskFactors
            ON -- define the linking condition here
WHERE   tblRel.symptomID = '1' AND 
        tblRel.symptomID = '2' AND 
        tblRel.symptomID = '3'

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Answer 2

SELECT tblDiseases.disease as disease 
FROM tblRel 
   LEFT JOIN tblDiseases ON tblRel.diseaseID = tblDiseases.diseaseID
   LEFT JOIN tblRiskFactors ON tblRel.relation_column = tblRiskFactors.relation_column
WHERE tblRel.symptomID in (1,2,3)