求指教SQL函数解决思路_Sql Server

求指教SQL函数
[email protected]，求指教！！！
这个函数只是来算一下某一读者借了多少本书
create function numBook(@readerName varchar(20))
returns int
as
begin
declare @num int;
select COUNT(*) into @num
from t_borrow,t_reader2
where t_borrow.readerId=t_reader2.readerId
and [email protected]
group by readerId;
return @num;
end

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SQL code

create function numBook(@readerName varchar(20))returns intasbegindeclare @num int;select @num=COUNT(*) from t_borrow,t_reader2  where t_borrow.readerId=t_reader2.readerId  and [email protected]group by readerId;return @num;end--select count(*) into @num是Oracle中的语法
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探讨

oh。。。我错了，用group by只是同学建议我试试。。。现在去掉了，然后也改过来了，不报错了。多谢啊！那个，再弱弱的问，要怎么调用啊。。。