As a highly organized commercial industry, hotels can be classified into ( ).
A. commercial
B. resort
C. conventional
D. resident
第1题:
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
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