查询出EMP表中COMM字段为空的记录()
A、select * from emp where comm='';
B、select * from emp where comm=null;
C、select * from emp where nvl(comm)=0;
D、select * from emp where comm is null;
E、select * from emp where nvl(comm,0)=0;
A、select * from emp where comm='';
B、select * from emp where comm=null;
C、select * from emp where nvl(comm)=0;
D、select * from emp where comm is null;
E、select * from emp where nvl(comm,0)=0;
A、select ename,nvl(comm.,0)from emp B、select ename,null(comm.,0)from emp C、SELECT ename,NULLIF(comm,0)FROM emp D、SELECT ename,DECODE(comm.,NULL,0)FROM emp
A、在查询中,选择查询可以只选择表中的部分字段,通过选择一个表中的不同字段生成同一个表 B、在查询中,编辑记录主要包括添加记录、修改记录、删除记录和导入、导出记录 C、在查询中,查询不仅可以找到满足条件的记录,而且还可以在建立查询的过程中进行各种统计计算 D、以上说法均不对
A、select * from emp where hiredate>='19820101'; B、select * from emp where hiredate>=to_char('19820101','YYYYMMDD'); C、select * from emp where to_date(hiredate,'YYYYMMDD')>='19820101'; D、select * from emp where to_char(hiredate,'YYYYMMDD')>='19820101';
A、A.Select * From Emp Where EmpNO In('791','792','793') B、B.Select * From Emp Where EmpNO ='791' Or EmpNO='792' OR EmpNO='793' C、C.Select * From Emp Where EmpNO >='791' And EmpNO<='793' D、D.Select * From Emp Where EmpNO >'791' And EmpNO<'793'
A、A.SELECT last_name,12*salary* commission_pct FROM emp B、B.SELECT last_name,12*salary*(commission_pct,0)FROM emp C、C.SELECT last_name,12*salary*(nvl(commission_pct,0))FROM emp如果oracle第一个参数为空那么显示第二个参数的值,如果第一个参数的值不为空,则显示第一个参数本来的值 D、D.SELECT last_name,12*salary*(decode(commission_pct,0))FROM emp
A、Select * From Emp Where EmpNO Not In('791','792','793') B、Select * From Emp Where EmpNO !='791' AND EmpNO!='792' And EmpNO='793' C、Select * From Emp Where EmpNO <>'791' AND EmpNO<>792' And EmpNO=<>793' D、Select * From Emp Where EmpNO =!'791' AND EmpNO =!'792' And EmpNO =!'793'