WHERE子句導致語法錯誤在MySQL查詢

Question

考慮（某銀行）表：

賬戶

客戶

我想回到一切客戶編號，有多於 的客戶比銀行的一個帳戶

我的建議：

SELECT c.Client_id_number , c.firstName_client , c.lastName_Client , COUNT(a.Account_number) as number_of_accounts 
FROM Clients AS c 
LEFT JOIN Accounts AS a 
ON a.Client_id_number = c.Client_id_number 
GROUP BY Client_id_number 
WHERE number_of_accounts >= 2; 

但在WHERE子句會導致語法錯誤。爲什麼？

Answer 1

SELECT c.Client_id_number , c.firstName_client , c.lastName_Client , COUNT(a.Account_number) as number_of_accounts 
FROM Clients AS c 
LEFT JOIN Accounts AS a 
ON a.Client_id_number = c.Client_id_number 
GROUP BY Client_id_number 
HAVING COUNT(a.Account_number) >= 2; 

See this for correct SQL clasues order

Answer 2

SELECT Account_number, Client_id_Number 
FROM Accounts 
GROUP BY Account_number, Client_id_Number 
having count(*) > 1 

Answer 3

Where子句應該是組之前，

SELECT c.Client_id_number , c.firstName_client , c.lastName_Client , COUNT(a.Account_number) as number_of_accounts 
FROM Clients AS c 
LEFT JOIN Accounts AS a 
ON a.Client_id_number = c.Client_id_number 
WHERE number_of_accounts >= 2  
GROUP BY Client_id_number;