世界城市研究的主要内容是什么？
You need to modify the STUDENTS table to add a primary key on the STUDENT_ID column. The table is currently empty. Which statement accomplishes this task?（） ALTER TABLE students ADD PRIMARY KEY _ id;。 ALTER TABLE students ADD CONSTRAINT PRIMARY KEY (student_id);。 ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY student_id;。 ALTER TABLE students ADD CONSTRAINT stud_id_pk PRIMARY KEY (student_id);。 ALTER TABLE students MODIFY CONSTRAINT stud_id_pk PRIMARY KEY (student_id)。
You have two databases， FINDB and PAYDB， on single operating system and using Optimal Flexible architecture （OFA）. FINDB is functional and is currently being accessed by the users. While starting up the instance for the PAYDB database you get the following error： ORA-01081： cannot start - already running ORACLE - shut it down first Which environmental variable would you set before starting up the PAYDB database to overcome this error？（） ORA_PATH。 ORACLE_SID。 ORACLE_BASE。 ORACLE_HOME。 LD_LIBRARY_PATH。
下列关于给水系统的描述中，错误的是（）。 给水系统一般由给水泵.给水管道和阀门组成。 按水源种类可将给水系统分为地表水和地下水给水系统。 按使用目的可将给水系统分为生活用水.生产用水和消防给水系统。 镀锌钢管.不锈钢管.PPR管等是目前建筑给水的主要管材。 PVC材质的给水管目前在我国广泛使用。
A customer is cost-justifying advanced software functions of several disk subsystem vendors.Which of the following software features of the Storwize V7000 are provided at no charge?（） Easy Tier, FlashCopy, Thin Provisioning 。 Easy Tier, External Virtualization, FlashCopy 。 Easy Tier, Metro/Global Mirror, Thin Provisioning 。 Metro/Global Mirror, FlashCopy, External Virtualizatio。
Which command will display the current control key settings？（）
