1. řešení pomocí where
podmínka:
SELECT t1.valuesum, t1.codebook
FROM (
SELECT SUM( s.value ) AS valuesum, s.codebook
FROM stock s
GROUP BY s.codebook
) t1
WHERE t1.valuesum in (SELECT MAX( t2.valuesum ) AS total
FROM (
SELECT SUM( s2.value ) AS valuesum, s2.codebook
FROM stock s2
GROUP BY s2.codebook
)t2
)
SQL Fiddle Demo
2. řešení pomocí having
podmínka:
SELECT max(t1.valuesum), t1.codebook
FROM (
SELECT SUM( s.value ) AS valuesum, s.codebook
FROM stock s
GROUP BY s.codebook
) t1
GROUP BY t1.codebook
HAVING max(t1.valuesum) = (SELECT MAX( t2.valuesum ) AS total
FROM (
SELECT SUM( s2.value ) AS valuesum, s2.codebook
FROM stock s2
GROUP BY s2.codebook
)t2
)