已知员工表emp(empno,ename,job,sal)其中empno员工编号,ename员工姓名,job员工的职位,sal员工的工资。若要查看工资大于2000的员工的信息,则正确的sql语句是()
A. select * from emp;
B. select * from emp where sal>2000;
C. select * emp where sal>2000 ;
D. select * from emp sal>2000;
查看答案
下列sql语句能够正确执行的是()
A. select * from teacher where name in(test,test2);
B. select * from teacher where name (test,test2);
C. select * from
D. select * from teacher where name !=(test,test2);teacher where name not
共模抑制比是差动放大电路中__信号的__与__信号的__之比
已知关系:学生表stu(学号id,姓名name,籍贯address,年龄age,电话tel),下列说法错误的是()
A. select name from stu where age>18;
B. select * from stu where tel is null;
C. select name from stu where address in (河北,河南,徐州);
D. select name from stu where address not in(河北,河南,徐州)
火灾后被抢救下来的双氧水,其包装外面必须用雾状水淋洗后才能重新放回仓库()
A. 是
B. 否