在Oracle的文档The Query Optimizer中,在
View Merging下,我找到了以下信息
原文链接：https://www.f2er.com/oracle/205310.htmlThe view merging optimization applies to views that contain only
selections,projections,and joins. That is,mergeable views do not contain
set operators,aggregate functions,DISTINCT,GROUP BY,CONNECT BY,and so on.
(emphasis mine)
然而,我只能猜测这样的投射实际上是指什么.
