Question

I’ve got a table with 500.000 records filled with Twitter updates. Then I’ve got a table with user info.

I basically need all the Twitter records of the people in my user table.

I can do it with this SELECT IN query:

SELECT *
FROM STATUS WHERE twitterUserID
IN (    
    SELECT twitteruserid
    FROM accountLink
)

But that’s obviously very slow.

I then tried to do it with a join, but it only shows 7 records. No idea why.

SELECT status . * , accountLink.userId, accountLink.twitterUserId
FROM status
JOIN accountLink
ON status.twitterUserId = accountLink.twitterUserId

Does anyone know what could cause this behaviour and how to solve it?

Answer 1

Try changing it to this:

SELECT status.* , accountLink.userId, accountLink.twitterUserId
FROM status
LEFT JOIN accountLink
ON status.twitterUserId = accountLink.twitterUserId

I suspect that there aren’t matches for all the records between status and account link. Doing a left join will select every status regardless of whether or not accountLink has a match.