Question

我有以下表格：

companyContacts
addresses
states
phoneNumbers

我需要在addresses，states和phoneNumbers上进行LEFT JOIN。我需要将phoneNumbers和addresses与companyContacts联系起来，并且需要将states与addresses联系起来。

我可以选择以下内容来抓取所有内容。但是，如果有人有地址而不是电话号码，则不会返回结果。我该如何制作phoneNumbers和addresses以及companyContacts加入？

SELECT * FROM
    companyContacts AS c
    LEFT JOIN phoneNumbers AS p
        ON c.entityID = p.entityID
    LEFT JOIN addresses AS a
        ON p.entityID = a.entityID
    LEFT JOIN states AS s
        ON a.stateID = s.id

Answer 1

听起来你想要这个：

SELECT * 
FROM  companyContacts AS c
LEFT JOIN phoneNumbers AS p
   ON c.entityID = p.entityID
LEFT JOIN addresses AS a
   ON c.entityID = a.entityID
LEFT JOIN states AS s
   ON a.stateID = s.id

如果您companyContacts.entityId加入phoneNumbers和addresses，即使没有电话号码或地址，您也会返回记录。你用它写的方式需要存在的电话号码才能返回地址

MySQL LEFT JOIN来自同一源表的多个表

1 个答案: