(2013工商银行)现在关数据表:客户表customer(ctno,ctname),产品表product(pno,pname),销量表cpnumber(ctno,pno,salesnumber)。下列SQL语句中不能实现“统计所有购买了产品‘基金1号’客户数量”功能的是( )
A.
select COUNT(*) from customer where ctno = (select ctno from cpnumber where pno= ( select pno from product where pname= `基金1号`))
B.
select COUNT(*) from cpnumber where pno=(select pno from product where pname=`基金1号`)
C.
select COUNT(cp.ctno) from product p , cpnumber cp where p.pname=`基金1号` and p.pno=cp.pno
D.
select COUNT(*) from product p , cpnumber cp where p.pname=`基金1号` and p.pno=cp.pno