单选题

积分result表中有A B C D四列，要...

Question

积分result表中有A B C D四列，要求：
1）当A列值大于等于B列时，选择A列否则选择B列
2）当C列值大于等于D列时，选择C列否则选择D列
用SQL语句实现正确的是：（      ）

A. select ( when A&gt=B then A else B ) MAX_AB, ( when C&gt=D then C else D ) MAX_CD from result

B. select (case when A&gt=B then A else B ) MAX_AB, (case when C&gt=D then C else D ) MAX_CD from result

C. select (case when A&gt=B then A else B end) MAX_AB, (case when C&gt=D then C else D end) MAX_CD from result

D. select case when A&gt=B then A else B end MAX_AB, case when C&gt=D then C else D end MAX_CD from result