gistfile1.txt

SELECT count( a.ticket_id ), t.name 
FROM article a 
    INNER JOIN article_type t 
        ON a.article_type_id = t.id
    INNER JOIN article_sender_type st 
        ON a.article_sender_type_id = st.id
WHERE a.id = (
    SELECT MIN(id) 
    FROM article a2 
    WHERE a2.ticket_id = a.ticket_id
)
   AND a.create_time BETWEEN '2017-12-21 15:00:00' AND '2017-12-21 21:00:00'
GROUP BY a.article_type_id