20151220 OCP 047 b 20-50

24.a subquery is called a single-row subquery when 

a.the inner query returns a single value to the main query

顾名思义，对于主查询只返回一个值

34.evaluate the following statement;

insert all 

when order_total<10000 then 

into small_orders 

when order_toal>10000 and order_total<20000 then

into medium_orders

when order_total>200000 then

into large_orders 

select order_id,order_total,customer_id from orders;

which is true ?

a.they are evalauated by all the three when clauses regardlisee of the results of 

the evaluation of any other when clause

这道题考查multitable insert

有条件的insert all,select 提取来的数据会一次进入三个when判断条件

36.which two statements are true regarding roles?

a. a role can be granted to itself

角色不能授予自己

b.a role can be granted to public

public 是oracle的自带角色，指全部用户

c.a user can be granted only one role at any popint of time

。。。

这个明显不对

d.the revoke command can be used to remove privileges but not roles 

from other users

revoke[proivilege](on project) from user/role

e.roles are named groups of related privileges that can be granted to users of other roles

一组相关的权限被命名为角色，角色可以授予用户或是其他角色

42.you executed the follwoing sql statements in the given order;

create table orders

(order_id number(3) primary key,

order_date date,

custumer_id numer(3)):

insert into orders values (100,'100-mar-2007,222);

alter table orders modify order_date not null;

update orders set customer_id=333;

delete from order;

the dleete statement results in the following error;

error al line 1;

ORA-00942;TABLE OR VIEW DOES NOT EXIST

what would be the outcome?

d,all the statements up to the alter table statement woulf be comited and the outcome of the update sytate,ent is 

retaiind uncomming within the session

所有的ddl,dcl操作都会隐式的将命令前面未提交的事务提交。

命令失败不会讲命令失败前的视图提交掉，也不会回滚掉

48.Flash drop 用来恢复被误drop掉的表的恢复，同时还能恢复所有索引以及触发器的授权。此外，唯一约束，主键约束和非空约束也将被恢复。外键约束则不可以恢复