I'm porting a custom PHP feature to be part of a Wordpress plugin.
At present, my USERS table has a field (let's call it FLAG) which my MySQL query needs to filter on, eg:
SELECT custom-data FROM custom-table JOIN users ON some-match WHERE some-condition AND users.flag='1' GROUP BY username
Obviously, within my WordPress plugin, I have implemented
flag as user-meta.
But how can I use this in a MySQL query?