是否可以加入这些MySQL表格Attendee和Message？

So i have got these two MySQL tables. I am trying to join the two statements to find out which TelNumber the senderNo is associated with:

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I have tried this query but it only returns the messages that have a associated attendee, not ones that dont have an associated telNumber registered on the database.

SELECT Attendee.`ownerName`, Attendee.`businessName`,Messages.`messageID`, Messages.`senderNo`, Messages.`messageContent`,Messages.`timestamp`,Messages.`type`,Messages.`viewed` 
FROM Messages 
INNER JOIN Attendee ON Messages.`senderNo`= Attendee.`telNumber` OR Attendee.emailAddress

The or equals part is because senderNo can also contain and Email address in which the type would be Email

Thanks in advance.

You can't use OR to compare one column to two columns like that, you need to do both comparisons separately and join them with OR.

ON Messages.senderNo = Attendee.telNumber OR Messages.senderNo = Attendee.emailAddress

You can also use IN to compare a value to multiple things:

ON Messages.senderNo IN (Attendee.telNumber, Attendee.emailAddress)

To get messages that don't have a matching attendee, use LEFT JOIN instead of INNER JOIN.

  1. The structure of your query is incorrect. After the OR, it should be

    Messages.senderNo = Attendee.emailAddress

  2. To get the messages that don't have an associated telNumber, you need to use LEFT OUTER JOIN instead of INNER JOIN