Question

我编写此SQL查询是为了获得特定患者的剩余收益，由于患者ID是唯一的，因此期望它返回一行，但它会不断返回多行。我该如何解决？ DBMS是MySql

 select Plan.pBenefitMax - sum(Transaction.employerTotal) as RemainingBenefit
 from Patient
 inner join Plan on Patient.pPlanId = Plan.planId
 inner join Transaction on Patient.patientId = Transaction.tPatientId
  where Patient.patientId = 1
 Group by Plan.pBenefitMax;

Answer 1

如果没有得到一行，则说明您有重复的PatientId值，或者PatientId已链接到多个计划。

  SELECT Plan.pBenefitMax - 
         (SELECT SUM(`Transaction`.employerTotal) 
            FROM `Transaction` 
           WHERE `Transaction`.tPatientId = Patient.patientId) 
         AS RemainingBenefit
    FROM Patient
    JOIN Plan ON Patient.pPlanId = Plan.planId
   WHERE Patient.patientId = 1;

SQL查询不断返回多行

1 个答案: