SQL分組計數大於

Question

我有這個SQL來統計組，但是我想說計數大於1的地方，有人可以幫忙，因為它目前不起作用？

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

Answer 1

你應該把這個條件在HAVING -clause：

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

HAVING之后評估GROUP BY而WHERE之前評估，這意味着WHERE -clauses將在recordlevel過濾，而HAVING -clauses上聚集過濾器。

有關更詳細的說明，請檢查SQL-在哪里使用VS

我還建議您閱讀SELECT語句的邏輯處理順序