ORACLE内部操作

当执行查询时,ORACLE采用了内部的操作. 下表显示了几种重要的内部操作.

ORACLE Clause	内部操作
ORDER BY	SORT ORDER BY
UNION	UNION-ALL
MINUS	MINUS
INTERSECT	INTERSECT
DISTINCT,MINUS,INTERSECT,UNION	SORT UNIQUE
MIN,MAX,COUNT	SORT AGGREGATE
GROUP BY	SORT GROUP BY
ROWNUM	COUNT or COUNT STOPKEY
Queries involving Joins	SORT JOIN,MERGE JOIN,NESTED LOOPS
CONNECT BY	CONNECT BY