选择 AS 在 interbase 中不工作

Posted 2023-03-24

【中文标题】选择 AS 在 interbase 中不工作

【英文标题】：Select AS not working in interbase

【发布时间】：2011-02-18 13:52:46

【问题描述】：

作品

select payeeid, EXTRACT(WEEKDAY FROM checkdate) as DOW, 
(bankcleared - checkdate) as DateDiff  
from Master  
where (bankcleared is not null)  
order by payeeid, DOW, DateDiff  

将DateDiff 添加到Where - 不起作用

select payeeid, EXTRACT(WEEKDAY FROM checkdate) as DOW, 
(bankcleared - checkdate) as DateDiff  
from Master  
where (bankcleared is not null)  AND (DateDiff >= 1)  
order by payeeid, DOW, DateDiff  

【问题讨论】：

对不起，我也想问....为什么将 DateDiff 添加到 where 会导致错误 - DateDiff Column unknown

因为 DATEDIFF 是一个内置函数，它检索两个日期时间戳之间的日期部分差异。

【参考方案1】：

您只能在 GROUP BY、ORDER BY 或 HAVING 子句中使用列别名。

标准 SQL 不允许您在 WHERE 子句中引用列别名。施加此限制是因为在执行 WHERE 代码时，可能尚未确定列值。

试试这个

select payeeid, EXTRACT(WEEKDAY FROM checkdate) as DOW, 
(bankcleared - checkdate) as DateDiff
from Master
where (bankcleared is not null) AND ((bankcleared - checkdate)>= 1)
order by payeeid, DOW, DateDiff 

有关更多信息，请访问这些链接

Can you use an alias in the WHERE clause in mysql?

Unknown Column In Where Clause

【参考方案2】：

select payeeid, 
       EXTRACT(WEEKDAY FROM checkdate) as DOW, 
       (bankcleared - checkdate) as DateDiff
from Master
WHERE (bankcleared is not null) 
AND   ((bankcleared - checkdate)>= 1)
Order by  payeeid, DOW, DateDiff