SQL

where Cname like 'DB\Design' escape'\'; --escape'\' 表示'\'--

聚集函数select count(distinct sno)

select avg(grade)

select max(grade)

select sum(ccredit)

聚集函数只能用于select字句和group by 中的having字句

select sno

from sc

group by sno

having count(*)>3

having短句用于组，从中选择满足条件的组

 

转载于:https://www.cnblogs.com/Arvin-9/p/5124310.html

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