[7] Oracle文档。半连接:A semijoin returns rows that match an EXISTS subquery without duplicating rows from the left side ofthe predicate when multiple rows on the right side satisfy the criteria of thesubquery.
[8] Oracle文档,反半连接:An antijoin returns rows from theleft side of the predicate for which there are no corresponding rows on theright side of the predicate. It returns rows that fail to match (NOT
IN) the subquery on the right side.