在PL/SQL语句块中,跳出循环体所用的语句是: ______。
A.break
B.continue
C.exit
D.next
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华为虚拟镜像管理系统VIMS是以下哪些功能特性的基础?()
A. 存储精简置备
B. 虚拟机快照
C. 存储迁移
D. 链接克隆
下面哪个语句关于GROUP BY 和HAVING语句的使用是正确的?()
A.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_IDHAVING AVG(SALARY) > 3000;
B.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_ID ,DEPARTMENT_IDHAVING AVG(SALARY) > 3000;
C.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY AVG(SALARY)HAVING AVG(SALARY) > 3000;
D.SELECT JOB_ID , DEPARTMENT_ID , AVG(SALARY)FROM EMPLOYEES GROUP BY JOB_ID , DEPARTMENT_IDHAVING SALARY > 3000;
游标的操作包括:()
A. open
B. fetch
C. execute
D. quit
E. close
在《假如给我三天光明》一书中,被海伦认为是“帝王之树”的是()。
A. 杨树
B. 法国梧桐
C. 槐树
D. 橡树