未知列在WHERE子句與加入

Question

我想加入3表一列總和已經與另一列

這裏進行比較是我的查詢

SELECT 
    *, `e`.`id` AS `event_ac_id`, 
    SUM(CASE WHEN trans.gift_transaction_status = 1 
       THEN trans.event_gift_amount 
       ELSE 0 END) as amount 
FROM 
    `tbl_event_category` `cat` 
LEFT JOIN 
    `tbl_event` `e` ON e.event_category = cat.id 
LEFT JOIN 
    `tbl_organisation` `org` ON e.organisation_id = org.id 
LEFT JOIN 
    `tbl_event_gift_transaction` `trans` ON e.id = trans.event_id 
WHERE 
    cat.type ='campaign' AND is_approved=1 
    AND e.funding_goal_amount <= amount 
GROUP BY 
    `event_ac_id` 
LIMIT 8 

異常（數據庫除外）「警予\分貝\異常 '與消息 ' SQLSTATE [42S22]：柱未發現：在 1054未知列 '量' 'where子句'

Answer 1

您需要了解SQL是從右向左評估的。因此，當MYSQL解析器查找amount列時，它不會被找到並因此出現錯誤。

的manual說：

「A select_expr可以給出使用AS ALIAS_NAME一個別名的別名是用作表達式的列名 ，並且可以在GROUP BY使用， ORDER BY，或HAVING。條款「。

和

標準SQL不允許你引用列別名在WHERE子句 。施加此限制是因爲當執行WHERE代碼 時，列值可能尚未確定。

你可以試試這個：

SELECT *, `e`.`id` AS `event_ac_id`, 
    SUM(CASE WHEN trans.gift_transaction_status = 1 THEN trans.event_gift_amount 
    ELSE 0 END) as amount 
FROM `tbl_event_category` `cat` LEFT JOIN `tbl_event` `e` 
     ON e.event_category=cat.id 
LEFT JOIN `tbl_organisation` `org` ON e.organisation_id=org.id 
LEFT JOIN `tbl_event_gift_transaction` `trans` ON e.id=trans.event_id 
WHERE cat.type ='campaign' 
AND is_approved=1 
HAVING e.funding_goal_amount <= amount 
GROUP BY `event_ac_id` LIMIT 8 

Answer 2

過濾器上的總價值爲基礎在具有

可能是你需要這個

SELECT *, `e`.`id` AS `event_ac_id`, 
    SUM(CASE WHEN trans.gift_transaction_status = 1 THEN trans.event_gift_amount 
    ELSE 0 END) as amount 
FROM `tbl_event_category` `cat` LEFT JOIN `tbl_event` `e` 
     ON e.event_category=cat.id 
LEFT JOIN `tbl_organisation` `org` ON e.organisation_id=org.id 
LEFT JOIN `tbl_event_gift_transaction` `trans` ON e.id=trans.event_id 
WHERE cat.type ='campaign' 
    AND is_approved=1 
    HAVING e.funding_goal_amount <= amount 
    GROUP BY `event_ac_id` LIMIT 8 

Answer 3

計算值，不能在WHERE條款。只有實際的列需要在那裏使用。

如果要過濾事後WHERE條款已被執行，則可以使用HAVING聲明