从视图中获取最大计数

Question

我创建了一个视图，允许我查看医生的预约次数。

查看代码：

create view DocApps as
select d.doctorid, d.surname ||','|| d.given as "Doctor", count(*) as "Appointments"
from doctor d, appointment
where d.doctorid=appointment.doctorid
group by d.doctorid, d.surname, d.given;

我现在需要显示预约次数最多的医生，我使用了这段代码，因为它在之前的查询中有效：

select Doctor, Appointments
from docapps
where Appointments in (select max(Appointments)
from docapps);

但它返回 "Appointments"：无效的标识符，当我指定它是那个时？

Answer 1

使用双引号 (") 会使表和列等对象名称区分大小写，这就是导致您出现问题的原因。只需将它们从视图声明中删除就可以了：

CREATE VIEW DocApps AS
SELECT   d.doctorid, d.surname ||','|| d.given AS Doctor, 
         COUNT(*) AS Appointments
FROM     doctor d, appointment
WHERE    d.doctorid=appointment.doctorid
GROUP BY d.doctorid, d.surname, d.given;

从视图中获取最大计数

Getting max count from a view

sql

oracle

view

count

max