有一个商品信息表(表名:ProInfo) ,表的字段为 ProID(商品编号) ,P
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Select ProCatg, AVG(ProPrice) From ProInfo
Select ProCatg, AVG(ProPrice) From ProInfo Group By ProCatg
Select AVG(ProPrice) From ProInfo Group By ProCatg
Select AVG(ProPrice) From ProInfo
参考答案: