使用三个表

Question

表1

HospitalID   HospitalName                     Address
    1        Andalusia Regional Hospital      Andaluisa
    2        Baypointe Hospital               New York
    3        Axa Hospital                     California

表2

ID   HospitalID   ClinicName
 1     1          Women Health
 2     1          Man Health
 3     1          Travel Health
 4     1         Cardiology
 5     2         internal medicine
 6     3         Cardiology

表3

Id  HospitalID  TargetHospitalID  DistanceKm
 1      1              2           45
 2      1              3           95
 3      2              3           15

我在HospitalID = 1医院。（心脏病学）

我需要找到离我这里最近的医院。

select top 1 TargetHospitalID 
from Table3 
where HospitalID = 1 
order by DistanceKm

此代码的结果是TargetHospitalID = 2。但是，Baypointe医院没有心脏病科。

我需要找一家心脏病科最近的医院。怎么做这个查询？谢谢你的帮助。

Answer 1

您需要修改将其与Table2连接并按部门过滤的查询。

select top 1 t3.TargetHospitalID 
from Table3 t3 INNER JOIN Table2 t2 ON t3.TargetHospitalID = t2.HospitalID
where t3.HospitalID=1 and t2.ClinicName = 'Cardiology'
order by t3.DistanceKm