单选题

select * from tab ...

Question

select * from tab where colA=’1’ union select * from tab where colB=’2’ 与此查询语句等价的选项是

A. select * from tab where colA=&rsquo1&rsquo and colB= &rsquo2&rsquo

B. select * from tab where colA=&rsquo1&rsquo or colB= &rsquo2&rsquo

C. select * from tab where colA=&rsquo1&rsquo

D. select * from tab where colB=&rsquo2&rsquo