Question

SELECT 
    COUNT(a)/COUNT(s)*100 as aratio, 
    COUNT(b)/COUNT(s)*100 as bratio, 
    COUNT(c)/COUNT(s)*100 as cratio, 
    COUNT(a), 
    COUNT(b), 
    COUNT(c), 
    COUNT(s) 
FROM 
    (SELECT COUNT(cid) as a FROM images WHERE width > height AND category_id = 4 GROUP BY cid) as aq, 
    (SELECT COUNT(cid) as b FROM images WHERE width < height AND category_id = 4 GROUP BY cid) as bq, 
    (SELECT COUNT(cid) as c FROM images WHERE width = height AND category_id = 4 GROUP BY cid) as cq, 
    (SELECT COUNT(cid) as s FROM images WHERE category_id = 4 GROUP BY cid) as sq;

How can i make this request more effective?

Answer 1

it is possible with using WITH. Move all queries to WITH and modify them a little: change COUNT(cid) to COUNT(DISTINCT cid) and remove GROUP BY clause at all.