某用户希望显示补助非空的所有雇员信息,应该使用哪条语句()
A. SELECTename,sal,commFROMempWHEREcomm.<>null;
B. SELECTename,sal,commFROMempWHEREcomm.ISNOTnull;
C. SELECTename,sal,commFROMempWHEREcomm.<>0;
D. SELECTename,sal,commFROMempWHEREcomm.ISNULL;
以下哪条语句是错误的?()
A. SELECTename,salsalaryFROMempORDERBYsal;
B. SELECTename,salsalaryFROMempORDERBYsalary;
C. SELECTename,salsalaryFROMempORDERBY3;
D. SELECTenameFROMempORDERBYsalDESC;
DEFINE命令可用于定义哪种变量?()
A. NUMBER
B. CHAR
C. VARCHAR2
DATE
以下哪条语句是正确的?()
A. SELECTdeptno,sum(sal)FROMemp;
B. SELECTdeptno,sum(sal)FROMempWHEREavg(sal)>2000GROUPBYdeptno;
C. SELECTdeptno,sum(sal)FROMempGROUPBYdeptnoHAVINGavg(sal)>2000;
D. SELECTdeptno,sum(sal)FROMempWHEREavg(sal)>2000ORDERBYdeptno;