要查询book表中所有书名中包含“计算机”的书籍情况,可用( )语句。
A. SELECT * FROM book WHERE book_name LIKE ‘%计算机%’
B. SELECT * FROM book WHERE book_name LIKE ‘计算机%’
C. SELECT * FROM book WHERE book_name = ‘计算机*’
D. SELECT * FROM book WHERE book_name = ‘计算机%’
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查询course表中的前5行,正确的语法是( )。
A. select top 5 * from course
B. select top(5) from course
C. select top 5 from course
D. select top(5*) from course
select * from student where sno=’05880101’ union select * from student where sno=’05880102’ 与此查询语句等价的选项是( )。
A. select * from student where sno=’05880101’ and sno= ’05880102’
B. select * from student where sno=’05880101’ or sno= ’05880102’
C. select * from student where sno=’05880101’
D. select * from student where sno=’05880102’
由两个模数分别为M和N的计数器级联成的计数器,其总的模数为
A. M
B. N
C. MN
D. M/N
D/A转换器的转换时间的数值越小,表示D/A转换器工作速度( )。
A. 越高
B. 越低
C. 不能确定
D. 与之无关