• 2022-06-07
    查询book表中每类图书的平均单价,结果只显示平均单价大于30的图书类别名和平均单价,以下SQL语句正确的是?
    A: select 图书类别,avg(单价)from bookwhere 单价 >= avg(单价);
    B: select 图书类别,avg(单价)from bookgroup by 图书类别;
    C: select 图书类别,avg(单价)from bookgroup by 图书类别having avg(单价) > 30;
    D: select 图书类别,avg(单价)from bookgroup by 图书类别where avg(单价) > 30;
  • 举一反三