在MySQL查询中获得不寻常的计数

Question

在下面的查询中我得到了一些奇怪的结果 - 具体来说，我得到了两个类别（当前年份和所有时间）相同的计数，我无法弄清楚为什么会这样。这是我的疑问：

SELECT eventlist.isid, eventlist.name, COUNT(currentyearcount.arid) AS currentyearcount, COUNT(allreports.arid) AS allreports
FROM eventlist
LEFT JOIN artist_reports currentyearcount ON eventlist.isid = currentyearcount.CompanyID AND currentyearcount.event_year = 2015
JOIN artist_reports allreports ON eventlist.isid = allreports.CompanyID
GROUP BY eventlist.isid

我得到的结果如下：

isid    name    currentyearcount  allreports
1234    Name1   33                33
5678    Name2   105               105
9012    Name3   0                 63

我不确定为什么Name3会为currentyearcount显示为0，因为当前还没有任何报告，所以他们都应该显示为0。

更新：感谢Aleksandar的评论，这是正确的查询：

SELECT eventlist.isid, eventlist.name, SUM(CASE WHEN artist_reports.arid IS NOT NULL AND artist_reports.event_year = 2015 THEN 1 ELSE 0 END) AS currentyearcount, SUM(CASE WHEN artist_reports.arid IS NOT NULL THEN 1 ELSE 0 END) AS totalcount
FROM eventlist
LEFT JOIN artist_reports ON eventlist.isid = artist_reports.CompanyID
GROUP BY eventlist.isid