Which two statements about sequences are true? （）
AYou use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value.
BYou use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence.
CYou use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.
DYou use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column.
EIf a sequence starting from a value 100 and incremented by 1 is used by more then one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence.
FYou use REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.
安装WINDOWS2000前，要检查下列哪些项目（）
A、与UPS之间的连接
B、第三方软件
C、防病毒软件
D、主板BIOS
A customer reports that error messages occasionally appear and quickly disappear. Which of thefollowing is the BEST place for a technician to begin troubleshooting this issue?（）
A、Run a System Restore
B、Check Device Manager
C、Check the Event Logs
D、Check the System Information
有三个关系表R、S和T如下，其中三个关系对应的关键字分别为A，B和复合关键字(A,B)。表T的记录项(b,q,4)违反了（ ）。
A、实体完整性约束
B、参照完整性约束
C、用户定义的完整性约束
D、关系完整性约束
Identify three situations in which you would NOT be able to drop a tablespace. （）
Awhen the tablespace is online
Bwhen the tablespace has segments with data in it
Cwhen the tablespace is a default permanent tablespace for the database
Dwhen the tablespace contains a table that is currently being used by transactions
Ewhen the tablespace contains undo data that is needed to rollback an uncommitted transaction
You have executed this command to change the size of the database buffer cache： SQL> ALTER SYSTEM SET DB_CACHE_SIZE=2516582； System altered. To verify the change in size， you executed this command： SQL> SHOW PARAMETER DB_CACHE_SIZE NAME TYPE VALUE ------------------- ----------- ------------------ db_cache_size big integer 4194304 （4M） Why is the value set to 4194304 and not to 2516582（）
A、because 4194304 is the granule size
B、because 4194304 is the standard block size
C、because 4194304 is the largest nonstandard block size defined in the database
D、because 4194304 is the total size of data already available in the database buffer cache