Re: Optimize subquery, replace IN() with JOIN

[Rick James]

See if the comes closer to working:

    SELECT  a.id, a.title, a.alias
        FROM  content AS a
        WHERE  a.id =1842
          AND  EXISTS
        (
            SELECT  *
                FROM  category_content_se
                WHERE  content_id = a.id
                  AND  content_typ = 'actual' 
        )
        ORDER BY  a.date_add DESC
        LIMIT  10;

Indexes:
    content: INDEX(id, date) -- in this order
    category_content_se: INDEX(content_id, content_typ) -- in either order