SQL连接6个表

Question

请看一下图片。有 5 个表与指定 ID 的指定表相关。 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？有人可以帮我吗？

这是生成的查询（我使用的是左外连接）

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Appointment的主键，所以该表与所有6个表都有1:N关系。

在这种情况下，加入这 6 个表会产生具有重复数据的多行，就像Cartesian Product。例如如果（只针对一个id=46），则有：

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

您将在结果集中获得 3x6x4x2x2x5 = 1440 行，而您只需要 3+6+4+2+2+5 (+1) = @987654333 @ 行。这比所需的行数多 60 倍（并且列数更多）。

最好在每个查询中使用一个 JOIN 到一个（6 个）表中的一个（以及另一个查询以从基表 Appointment 获取数据）执行 6 个单独的查询。并在应用程序代码中组合 6 个查询的结果。基本查询和要连接到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 到 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

Answer 2

SELECT 
    Appointment.appointment_id, 
    Appointment.patient_id, 
    PatientInvestigaiton.investigation_name, 
    PatientInvestigaiton.investigation_id, 
    PatientTreatmentMedicine.medecine_id, 
    PatientTreatmentMedicine.medicinename, 
    PatientTreatmentMedicine.medicinetype, 
    PatientFindings.finding_id, 
    PatientFindings.finding_value, 
    PatientAdvice.advice_description, 
    PatientCC.cc_value, 
    PatientCC.cc_id, 
    PatientDiagonosis.diagonosis_name, 
    PatientDiagonosis.diagonosis_id
FROM 
    Appointment 
    LEFT OUTER JOIN PatientInvestigaiton     ON Appointment.appointment_id = PatientInvestigaiton.appointment_id AND Appointment.appointment_id='46'
    LEFT OUTER JOIN PatientTreatmentMedicine ON Appointment.appointment_id = PatientTreatmentMedicine.appointment_id 
    LEFT OUTER JOIN PatientFindings          ON Appointment.appointment_id = PatientFindings.appointment_id 
    LEFT OUTER JOIN PatientDiagonosis        ON Appointment.appointment_id = PatientDiagonosis.appointment_id 
    LEFT OUTER JOIN PatientCC                ON Appointment.appointment_id = PatientCC.appointment_id 
    LEFT OUTER JOIN PatientAdvice            ON Appointment.appointment_id = PatientAdvice.appointment_id

Answer 3

SELECT {TABLE1}.appointment_id,{OTHER FIELDS} FROM {TABLE1}
    JOIN {TABLE2} ON {TABLE1}.appointment_id = {TABLE2}.appointment_id
    JOIN {TABLE3} ON {TABLE1}.appointment_id = {TABLE3}.appointment_id
    JOIN {TABLE4} ON {TABLE1}.appointment_id = {TABLE4}.appointment_id
    JOIN {TABLE5} ON {TABLE1}.appointment_id = {TABLE5}.appointment_id
    JOIN {TABLE6} ON {TABLE1}.appointment_id = {TABLE6}.appointment_id
    JOIN {TABLE7} ON {TABLE1}.appointment_id = {TABLE7}.appointment_id
    JOIN {TABLE8} ON {TABLE1}.appointment_id = {TABLE8}.appointment_id;

试试这个：

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 JOIN dbo.PatientInvestigaiton
        ON dbo.Appointment.appointment_id = dbo.PatientInvestigaiton.appointment_id
    LEFT JOIN dbo.PatientTreatmentMedicine
        ON dbo.Appointment.appointment_id = dbo.PatientTreatmentMedicine.appointment_id
    LEFT JOIN dbo.PatientFindings
        ON dbo.Appointment.appointment_id = dbo.PatientFindings.appointment_id
    LEFT JOIN dbo.PatientDiagonosis
        ON dbo.Appointment.appointment_id = dbo.PatientDiagonosis.appointment_id
    LEFT JOIN dbo.PatientCC
        ON dbo.Appointment.appointment_id = dbo.PatientCC.appointment_id
    LEFT JOIN dbo.PatientAdvice
        ON dbo.Appointment.appointment_id = dbo.PatientAdvice.appointment_id
WHERE
    dbo.Appointment.appointment_id='46';