PRESERVE TABLE Clause This clause lets you retain the materialized view container table and its contents after the materialized view object is dropped. The resulting table has the same name as the dropped materialized view. 保留表條款
此子句允許在物理化視圖對象被刪除后，保留物化視圖容器表及其內容。 生成的表與刪除的實例化視圖具有相同的名稱。
drop materialized view MV_jobs PRESERVE TABLE后，USER_MVIEWS不見了MV_jobs,但是user_tables、dba_objects、dba_segments還有MV_jobs，select * from MV_jobs不會報錯 drop materialized view MV_jobs后USER_MVIEWS、user_tables、dba_objects、dba_segments都不見了MV_jobs，select * from MV_jobs不會報錯
conn hr/hr create materialized view MV_jobs refresh complete on demand as select * from jobs; drop materialized view MV_jobs PRESERVE TABLE; select * from MV_jobs;--有結果
