USE INDEX (PRIMARY) in mysql query, but getting a wrong syntax error?

Question

I'm trying to speed up a mySQL query by making it use the index, but for some reason it's telling me that the syntax is wrong. I can't figure out why, though. Any ideas?

All I did was add "USE INDEX (PRIMARY)"

SELECT a.listing_id FROM db_listings USE INDEX (PRIMARY)
a LEFT JOIN db_users u ON u.user_id=a.owner_id WHERE a.active=1 GROUP BY a.listing_id

Answer 1

Put the table alias a before the USE INDEX clause.