我在SQL此查詢,我想知道哪一個 (LEFT JOIN/INNER JOIN),我必須爲了提高速度,提高熟練程度使用INNER JOIN VS LEFT JOIN性能在SQL
UPDATE poker_hands f
INNER JOIN (poker_cards a, poker_cards b,
poker_cards c, poker_cards d, poker_cards e)
ON f.r1 = a.card_name
AND f.r2 = b.card_name
AND f.r3 = c.card_name
AND f.r4 = d.card_name
AND f.r5 = e.card_name
SET f.hand_type = 'Royal flush'
WHERE ((a.suit = b.suit AND b.suit = c.suit
AND c.suit = d.suit AND d.suit = e.suit)
AND (a.game_value = 14 AND b.game_value = 13
AND c.game_value = 12 AND d.game_value = 11 AND e.game_value = 10));
哪個服務器? [mysql]或[sql-server]? –
試一下,看看哪個跑得快。如果你無法區分差異,那麼你正在浪費你的時間來嘗試優化某些你甚至不確定需要優化的東西。而且,這兩件事並不相同,所以這個問題很奇怪。 – csmckelvey