Mysql 尝试在where子句中使用别名列名时出错

我的SQL查询有问题。我想按债务金额选择记录。金额根据与两个表的关系计算

这很好：

SELECT `i`.*, 
(i.amount_netto + (i.amount_netto * i.vat / 100)) - (SUM(p.amount_netto)) AS `debt`,
`e`.`name` AS `user_name`,
`e`.`surname` AS `user_surname`,
`c`.`name` AS `contractor_name`
FROM `invoices` AS `i` 
INNER JOIN `payments` AS `p` ON i.id = p.invoice_id 
INNER JOIN `employees` AS `e` ON i.employee_id = e.id 
INNER JOIN `contractors` AS `c` ON i.contractor_id = c.id 
GROUP BY `i`.`id` 
ORDER BY `debt` ASC

但是当我通过

debt

添加WHERE子句时，我得到一个错误：

Unknown column 'debt' in 'where clause'

查询如下所示：

SELECT `i`.*, 
(i.amount_netto + (i.amount_netto * i.vat / 100)) - (SUM(p.amount_netto)) AS `debt`, 
`e`.`name` AS `user_name`,
`e`.`surname` AS `user_surname`,
`c`.`name` AS `contractor_name`
FROM `invoices` AS `i` 
INNER JOIN `payments` AS `p` ON i.id = p.invoice_id 
INNER JOIN `employees` AS `e` ON i.employee_id = e.id 
INNER JOIN `contractors` AS `c` ON i.contractor_id = c.id 
WHERE `debt` > 1 
GROUP BY `i`.`id` 
ORDER BY `debt` ASC

---

为什么我不能在WHERE子句中访问

debt

，但可以在ORDER子句中访问？

SQL通常不允许您在WHERE、GROUP BY或HAVING子句中引用列别名。MySQL确实支持通过引用组中的列别名并具有

尝试将where查询更改为

WHERE (i.amount_netto + (i.amount_netto * i.vat / 100)) - (SUM(p.amount_netto)) > 1 GROUP BY i.id ORDER BY debt ASC

另一个选项是，可以使用子查询

SELECT * from (`i`.*, (i.amount_netto + (i.amount_netto * i.vat / 100)) - (SUM(p.amount_netto)) AS `debt`, `e`.`name` AS `user_name`, `e`.`surname` AS `user_surname`, `c`.`name` AS `contractor_name` FROM `invoices` AS `i` INNER JOIN `payments` AS `p` ON i.id = p.invoice_id INNER JOIN `employees` AS `e` ON i.employee_id = e.id INNER JOIN `contractors` AS `c` ON i.contractor_id = c.id  GROUP BY `i`.`id`) as newTable
WHERE `debt` > 1 ORDER BY `debt` ASC

---

债务

不是列，而是别名。列（表达式）别名在执行查询后才会解析，因此它们不能在WHERE子句中使用

例如，此查询不合法：

select foo + 3 as bar
from baz
where bar = 39

相反，您必须重写WHERE子句中的整个表达式：

select foo + 3 as bar
from baz
where foo + 3 = 39

---

此外，由于

债务

实际上是基于聚合的，因此不能在WHERE子句中对其进行筛选。相反，您必须在聚合后使用have来计算谓词。因此，您的查询应该是：

SELECT ...
FROM ...
GROUP BY ...
HAVING (i.amount_netto + (i.amount_netto * i.vat / 100)) - (SUM(p.amount_netto)) > 1
ORDER BY ...

请注意，因此您还可以执行以下操作：

SELECT ...
FROM ...
GROUP BY ...
HAVING debt > 1
ORDER BY ...

---

您应该使用表别名访问债务，它可以是

p.debt

或您使用的其他别名。我尝试使用p.debt，但没有任何反应。我仍然有一个错误：“where子句”中的未知列“p.debt”选择

i

*，（i.amount\u netto+（i.amount\u netto*i.vat/100））-（SUM（p.amount\u netto））作为

债务
，
e
名称
作为
用户名
，
e
作为
姓氏，
c
name
AS
contractor\u name
FROM
invoices
AS
i
internal JOIN
payments
AS
p
ON i.id=p.invoice\u id-internal JOIN
e
ON i.employee\u id=e.id
contractors
AS
ON.id=c.id=c.id（i.amount_netto+（i.amount_netto*i.vat/100））-（SUM（p.amount_netto））>1按债务ASC的i.id订单分组；我有一个关于无效使用分组函数的错误。啊，对不起…错过了您在这里使用分组的机会…尝试使用lc提出的解决方案，或者您可以尝试使用子查询