SQL加入6个表

Question

请看一下这个图片.有5个表与periodicTable相关,有的是givenID.现在我需要所有具有相同约会ID的数据......加入查询应该是什么？任何人都可以帮助我吗？

这是生成的查询(我正在使用Left outer Join)

SELECT     dbo.Appointment.appointment_id, dbo.Appointment.patient_id, dbo.PatientInvestigaiton.investigation_name, dbo.PatientInvestigaiton.investigation_id, 
           dbo.PatientTreatmentMedicine.medecine_id, dbo.PatientTreatmentMedicine.medicinename, dbo.PatientTreatmentMedicine.medicinetype, 
           dbo.PatientFindings.finding_id, dbo.PatientFindings.finding_value, dbo.PatientAdvice.advice_description, dbo.PatientCC.cc_value, dbo.PatientCC.cc_id, 
           dbo.PatientDiagonosis.diagonosis_name, dbo.PatientDiagonosis.diagonosis_id

FROM       dbo.Appointment LEFT OUTER JOIN

           dbo.PatientInvestigaiton ON dbo.Appointment.appointment_id = dbo.PatientInvestigaiton.appointment_id LEFT OUTER JOIN
           dbo.PatientTreatmentMedicine ON dbo.Appointment.appointment_id = dbo.PatientTreatmentMedicine.appointment_id LEFT OUTER JOIN
           dbo.PatientFindings ON dbo.Appointment.appointment_id = dbo.PatientFindings.appointment_id LEFT OUTER JOIN
           dbo.PatientDiagonosis ON dbo.Appointment.appointment_id = dbo.PatientDiagonosis.appointment_id LEFT OUTER JOIN
           dbo.PatientCC ON dbo.Appointment.appointment_id = dbo.PatientCC.appointment_id LEFT OUTER JOIN
           dbo.PatientAdvice ON dbo.Appointment.appointment_id = dbo.PatientAdvice.appointment_id

           where dbo.Appointment.appointment_id='46';

Answer 1

由于appointmnent_id是主键Appointment,因此该表1:N与所有6个表有关系.

这种情况下,加入这6个表将产生具有重复数据的多行,它就像一个Cartesian Product.例如,如果(仅一个id=46),有:

• 3行 PatientInvestigation
• 6行 PatientTreatmentMedicine
• 4行 PatientFindings
• 2行 PatientDiagnosis
• 2行 PatientCC
• 5行 PatientAdvice

你会1440在结果集中得到3x6x4x2x2x5 = 行,而你只需要3 + 6 + 4 + 2 + 2 + 5(+1)= 23行.这比所需的行多60倍(并且列数更多).

如果你在每个查询中使用一个JOIN到一个(在6个)表中执行6个单独的查询(以及从基表获取数据的另一个查询),则会更好Appointment.并在应用程序代码中组合6个查询的结果.基本查询和要加入第一个表的查询的示例:

基表:

SELECT 
    a.appointment_id, 
    a.patient_id
FROM 
    Appointment AS a
WHERE
    a.appointment_id = 46

Join-1 to PatientInvestigation:

SELECT 
    pi.investigation_name, 
    pi.investigation_id
FROM 
    Appointment AS a
      JOIN
    PatientInvestigation AS pi
        ON pi.appointment_id = a.appointment_id
WHERE
    a.appointment_id = 46