Question

我有下表：

patient: id, incidentCode, name, insurance, contactdetailsID
contactDetails: id, cityCode
lookup: id, lookupdescription
incident: id, date

患者加入联系方式，如：

inner join contactdetails on patient.contactdetailsid=contactdetails.id

患者加入了如下事件：

inner join incident on patient.incidentCode=incident.id

患者加入查找，如：

inner join lookup on patient.insurance = lookup.id

和联系人详细信息加入查找，如：

inner join lookup on contactdetails.citycode = lookup.id

现在我想从患者保险和contactdetails Citycode中选择Lookup.lookupDescription。我怎样才能做到这一点？在选择我也想要patient.name，patient.id，incident.date

Answer 1

例如

SELECT
  patient.id,
  lookup.lookupdescription,
  contactDetails.cityCode
FROM patient
INNER JOIN contactdetails on patient.contactdetailsid=contactdetails.id
INNER JOIN ...
INNER JOIN ...
INNER JOIN ...
WHERE patient.id = xy

顺便说一句：你提供的最后一个JOIN对我来说看起来不那么有意义？！看起来lookup.id是城市代码，同时也是保险号码？！

Answer 2

SELECT  d.lookupDescription,
        a.insurance,
        e.Citycode,
        a.name,
        a.id,
        c.date
FROM    patient a
        INNER JOIN contactdetails b
            ON a.contactdetailsid = b.id
        INNER JOIN  incident c
            ON a.incidentCode = c.id
        INNER JOIN lookup d
            ON a.insurance = d.id
        INNER JOIN contactdetails e
            ON e.citycode = d.id

要进一步了解联接，请访问以下链接：

Visual Representation of SQL Joins

多个表中的多个连接

2 个答案: