Question

我想加入3表一列总和必须与另一列进行比较

这是我的查询

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

异常（数据库异常）＆＃39; yii \ db \ Exception＆＃39;与消息＆＃39; SQLSTATE [42S22]：未找到列：1054未知列＆＃39;金额＆＃39;在＆＃39; where where＆＃39;

Answer 1

您需要了解SQL是从右到左进行评估的。因此，当MYSQL解析器查找amount列时，则找不到它，从而导致错误。

manual说：

“可以使用AS alias_name为select_expr提供别名。别名为用作表达式的列名，可以在GROUP BY中使用， ORDER BY或HAVING子句。“

和

标准SQL不允许您引用WHERE中的列别名条款。强制执行此限制是因为WHERE代码是执行后，列值可能尚未确定。

你可以试试这个：

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

聚合值的过滤器基于

可能是你需要这个

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

计算值不能出现在WHERE子句中。这里只需要使用实际的列。

如果要过滤AFTERWARDS已执行WHERE子句，则可以使用HAVING语句

带有加入的子句中的未知列

3 个答案: