单项选择题 Consider the following statement：   SQL> EXECUTE DBMS_STATS.GATHER_SHEMA_STATS （-  2> ownname => ‘OE’， -  3> estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE， -  4> method opt => ‘for all columns size AUTO’）；   What is the effect of ‘for all columns size AUTO’ of the METHOD_OPT option？（）

多项选择题 Examine the list of variables and their data types：  AME DATA Type  TS， TS1 TIMESTAMP  TSZ TIMESTAMP WITH TIME ZONE  TLZ TIMESTAMP WITH LOCAL TIME ZONE  IYM INTERVAL YEAR TO MONTH  IDS， IDSI INTERVAL YEAR To SECOND   Which three expressions using the new data and time data types are valid？（）

单项选择题 Whatistrueifyouwanttoswitchundotablespacesfromthecurrentone，calledUNDO1，toanewonecalledUNDO2？（）