選擇總和（金額）作爲條件對總

Question

我想，總交易用戶超過50000

SELECT sum(tractions.amount) as total , user_id FROM `tractions` where `total` > 50000 group by user_id 

我得到這個錯誤總

#1054 - Unknown column 'total' in 'where clause' 

詛咒

沒有總列在表中，但我應該怎麼寫條件？

Answer 1

你需要一個having子句聚集總數：

SELECT sum(tractions.amount) as total , user_id 
FROM `tractions` 
group by user_id 
HAVING total > 50000; 

編輯：

如果我寫這個查詢時，它看起來像這樣：

select t.user_id, sum(t.amount) as total 
from tractions t 
group by t.user_id 
having sum(t.amount) > 50000; 

我發現大寫關鍵字會分散注意力。我（幾乎）總是將我正在聚合的字段放在行首。我大量使用表別名，它們是表格的縮寫。我不會逃避標識符，因爲我從不在標識符中使用保留字或特殊字符。我把這個表達式放在having子句中，因爲。 。 。好吧，我曾經想過，並非所有數據庫都支持在having子句中使用列別名。

Answer 2

試試這個

SELECT sum(tractions.amount) as total , user_id FROM `tractions` where sum(tractions.amount) > 50000 group by user_id 

Answer 3

SELECT sum(tractions.amount) as total , user_id 
FROM `tractions` 
where sum(tractions.amount) > 50000 
group by user_id 

Answer 4

SELECT 
    sum(tractions.amount) as total, user_id 
FROM 
    `tractions` 
group by user_id 
having total > 50000;