sql server存储过程获取参加活动的人数

Question

我需要显示回答yes参加活动的人数。这里是我的SELECT语句至今：

SELECT TOP (100) PERCENT 
    dbo.tb_EventAttendance.WillAttend, 
    dbo.tb_Events.EventName, 
    dbo.tb_Events.EventDate 
FROM dbo.tb_EventAttendance 
INNER JOIN dbo.tb_Events ON dbo.tb_EventAttendance.EventID = dbo.tb_Events.dbID 
WHERE (dbo.tb_EventAttendance.WillAttend = 'Y') 
ORDER BY dbo.tb_Events.EventDate 

难道我使用COUNT函数，如果是在究竟这种情况呢？

Answer 1

您需要同时使用COUNT和GROUP BY（因为总COUNT）：

SELECT TOP (100) PERCENT dbo.tb_Events.EventName, dbo.tb_Events.EventDate, 
COUNT(dbo.tb_EventAttendance.WillAttend) as NumAttendees, 
FROM dbo.tb_EventAttendance INNER JOIN 
dbo.tb_Events ON dbo.tb_EventAttendance.EventID = dbo.tb_Events.dbID 
WHERE  (dbo.tb_EventAttendance.WillAttend = 'Y') 
GROUP BY dbo.tb_EventName, dbo.tb_Events.EventDate 
ORDER BY dbo.tb_Events.EventDate