oracle删除表空间

Oracle11g删除表空间语法描述：
DROP TABLESPACE tablespace_name
[ including contents [ and datafiles ] [ CASCADE CONSTRAINT ] ];
无选项 -- 当表空间为空才能删除；
including contents — 删除表空间及对象；
including contents and datafiles — 删除表空间、对象及数据文件；
includingcontents CASCADE CONSTRAINT — 删除关联；
including contents and datafiles cascade constraint -- 含前两项。