任務1:格碼大叔:http://baijiahao.baidu.com/s?id=1646813186987051634
任務2:
聚合函數 的練習:
use School
go
--聚合函數
select ClassNo,count(*) 'Count',avg(SqlServer) 'SqlServer Average',
avg(math) 'Math Average',
AVG(Gym) 'Gym Average',
MAX(Math) 'Math Maximum',
MIN(Math) 'Math Minimum'
from StuMark
--where...
group by ClassNo
--having avg(math)>71
go