Quelle est l'instruction SQL la plus rapide ?

Question

Quelle est l'instruction SQL la plus rapide ?

SELECT TOP 2 c1.Price, c2.Price, ..... c49.Price, c50.Price
FROM Table1 AS c1, Table2 AS c2, ..... Table49 AS c49, Table50 AS c50
WHERE c1.Date = c2.Date AND c2.Date = c3.Date ..... c49.Date = c50.Date
ORDER BY c1.ID DESC

        OR

SELECT TOP 2 c1.Price, c2.Price, ..... c49.Price, c50.Price
FROM (Table1 AS c1 
 INNER JOIN (Table2 AS c2 
    ........
  INNER JOIN (Table49 AS c49
   INNER JOIN Table50 AS c50
  ON c49.Date = c50.Date)
    ........
 ON c2.FullDate__ = c3.FullDate__)
ON c1.FullDate__ = c2.FullDate__)
ORDER BY c1.ID DESC";

J'ai besoin d'extraire 2 lignes de chaque tableau pour produire un résumé périodique. Quelle est l'instruction la plus rapide ?

Answer 1

Ignorer les JOIN dans la mesure du possible. Du point de vue des performances, les instructions Join ne sont pas du tout efficaces.