SQL group by count where count大于

Question

我有这个计算组的SQL，但我想说计数大于1的位置，任何人都可以帮助，因为它目前不起作用吗？

select Code, Qty, Count(Qty) from Product where ItemName = 'Banana'
and Count(Qty) > 1
Group by Code, Qty order by 3 desc

Answer 1

你应该把这个条件放在HAVING - 子句中：

select Code, Qty, Count(Qty) Qty
from Product 
where ItemName = 'Banana'
Group by Code
having count(Qty) > 1
order by 3 desc

HAVING在GROUP BY之后进行评估，而之前评估WHERE，这意味着WHERE - 子句将在记录级别上进行过滤，而HAVING - 子句会对聚合进行过滤

有关更详细的说明，请查看SQL - having VS where

我还建议您阅读Logical Processing Order of the SELECT statement