CTEsについて勉強中。
"Common table expressions are also known as the WITH clause, or subquery factoring."
via Check out this quote from Pro Oracle SQL Development : Best Practices for Writing Advanced Queries - https://learning.oreilly.com/nullhtml/471418_1_En_6_Chapter.xhtml
- CTEs
- WITH clause
- subquery factoring
は全て同じ。
"A correlated subquery is found in the SELECT or WHERE clause and references a column value from the outer query. An inline view is a subquery in the FROM clause."
via Check out this quote from Pro Oracle SQL Development : Best Practices for Writing Advanced Queries - https://learning.oreilly.com/library/view/pro-oracle-sql/9781484245170/html/471418_1_En_6_Chapter.xhtml
- SELECT or WHERE clauseにあるのがcorrelated subquery
- FROM clauseにあるのがinline view
- どちらも広義のsubquery
"In Oracle, this feature is also called subquery factoring, and the grammatically awkward “WITH clause.”"
via Check out this quote from Pro Oracle SQL Development : Best Practices for Writing Advanced Queries - https://learning.oreilly.com/library/view/pro-oracle-sql/9781484245170/html/471418_1_En_7_Chapter.xhtml
Oracleでは、
- common table expressions
- subquery factoring
- WITH clause
は同じものを指す。
"Oracle provides two ways to process hierarchical data: the original CONNECT BY syntax and the newer recursive common table expressions syntax (also known as recursive subquery factoring)."
via Check out this quote from Pro Oracle SQL Development : Best Practices for Writing Advanced Queries - https://learning.oreilly.com/library/view/pro-oracle-sql/9781484245170/html/471418_1_En_7_Chapter.xhtml
CTEsの応用とし、recursive queriesを一般的に学ぶのが良さそう。
