SQL4 択難易度 基礎

SELECT 文の句を書く正しい順番は？

正答

1. FROM → SELECT → WHERE → GROUP BY → HAVING → ORDER BY
2. SELECT → FROM → WHERE → GROUP BY → ORDER BY → HAVING
3. SELECT → WHERE → FROM → GROUP BY → HAVING → ORDER BY
4. SELECT → FROM → WHERE → GROUP BY → HAVING → ORDER BY

解説

書く順番は SELECT、FROM、WHERE、GROUP BY、HAVING、ORDER BY（最後に LIMIT）。実行される順番はこれと違い、FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY で評価される。WHERE で SELECT の別名が使えないのは、WHERE が SELECT より先に評価されるため。

参考: www.sqlite.org

clause-order