1. 查询空值 条件为<>’’ 是查不出结果的。
如果要查，应该使用 is not null 来查。
QUESTION NO: 135
View the Exhibit and examine the data in the PRODUCTS table. You need to display product
names from the PRODUCTS table that belong to the 'Software/Other1 category with minimum
prices as either $2000 or $4000 and no unit of measure. You issue thej following query:
Which statement is true regarding the above query? 
A. It executes successfully but returns no result.
B. It executes successfully and returns the required result.
C. It generates an error because the condition specified for PROD_UNIT_OF_MEASURE is not
valid.
D. It generates an error because the condition specified for the PROD_CATEGORY column is not
valid.
2. 多字段排序
order by 后面跟多个字段 colA,colB desc ----> 代表 colA asc,colB desc 默认的asc省略了。
3. DB_ULTRA_SAFE
DB_ULTRA_SAFE参数整合了DB_BLOCK_CHECKING, DB_BLOCK_CHECKSUM, 和 DB_LOST_WRITE_PROTECT三个参数。
http://www.linuxidc.com/Linux/2012-12/76118p2.htm
4. BLOCK CHANGE TRACKING
http://blog.csdn.net/tianlesoftware/article/details/6997647
5. rman backup expired
expired意思是控制文件有记录，但是在相应的目录下找不到它的存在，即已经被删除或者被移走
6.
QUESTION NO: 20
You are managing an Oracle Database 11g database with the ASM storage. The database is
having big file tablespaces. You want files to open faster and less memory to be used in the
shared pool to manage the extent maps.
What configuration would you effect to achieve your objective? (Choose all that apply.)
A. Set the ASM compatibility attribute for the ASM disk group to 11.1.0.
B. Set the RDBMS compatibility attribute for the ASM disk group to 11.1.0.
C. Set the COMPATIBLE initialization parameter for the ASM instance to 11.1.0.
D. Set the COMPATIBLE initialization parameter for the database instance to 11.1.0.
7. 数据泵导入
user remap_user
8.