este problema é chamado de
Relational Division SELECT boy_id
FROM boys_chocolates
WHERE chocolate_id IN ('$string')
GROUP BY boy_id
HAVING COUNT(DISTINCT chocolate_id) = ? -- <<== number of chocolates specified
exemplo:
SELECT boy_id
FROM boys_chocolates
WHERE chocolate_id IN (1,2,3,4)
GROUP BY boy_id
HAVING COUNT(DISTINCT chocolate_id) = 4
no entanto, se o
chocolate_id é exclusivo para cada boy_id , DISTINCT palavra-chave é opcional. SELECT boy_id
FROM boys_chocolates
WHERE chocolate_id IN (1,2,3,4)
GROUP BY boy_id
HAVING COUNT(*) = 4
ATUALIZAÇÃO 1
...quero escolher meninos da mesa que tenham exatamente os chocolates que mencionei. Nem mais nem menos...
SELECT boy_id
FROM boys_chocolates a
WHERE chocolate_id IN (1,2,3,4) AND
EXISTS
(
SELECT 1
FROM boys_chocolates b
WHERE a.boy_ID = b.boy_ID
GROUP BY boy_id
HAVING COUNT(DISTINCT chocolate_id) = 4
)
GROUP BY boy_id
HAVING COUNT(*) = 4
