mysql - 查询 MySQL 数据库

Question

谁能帮我在这个包含疾病风险因素的查询中添加第三个表。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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