MySQL没有每年返回

Question

我正在尝试让这个查询显示每年的空号和序号。唯一返回的年份是2006年。订单表本身有很多订单，范围从2006-2008年不等。

select empid, year(orderdate) as orderyear, count(empid) as ordercount
from orders
group by empid
order by year(orderdate);

Answer 1

如果您希望对每个empid和每年的订单进行计数，您也需要按年份分组：

SELECT   empid, YEAR(orderdate) AS orderyear, COUNT(empid) AS ordercount
FROM     orders
GROUP BY empid, YEAR(orderdate)
ORDER BY YEAR(orderdate);