假设进货表如下表所示,要统计各类产品的货物种数、平均单价、货物总量,下列SQL语句正确的是___________
A.
select 产品类型, sum(货物名称) as 货物种数, avg(单价) as 平均单价, sum(数量) as 货物总量 from 进货表 group by 产品类型
B.
select 产品类型, count(*) as 货物种数, avg(单价) as 平均单价, sum(数量) as 货物总量 from 进货表 group by 产品类型
C.
select 产品类型, count(*) as 货物种数, avg(单价) as 平均单价, count(数量) as 货物总量 from 进货表 group by 产品类型
D.
select货物名称, count(*) as 货物种数, avg(单价) as 平均单价, sum(数量) as 货物总量 from 进货表 group by 货物名称