sql - 如何修复我的 Oracle 11G SQL 查询？

Question

我无法弄清楚我在这里的查询做错了什么。

SELECT ORDER#, SUM(PAIDEACH * QUANTITY) AS TOTAL 
    FROM ORDERITEMS 
    WHERE TOTAL > 39.9 
    GROUP BY ORDER# 
    ORDER BY TOTAL DESC; 

这是我不断收到的错误：

"TOTAL": invalid identifier

Answer 1

由于您希望在聚合函数上有一个谓词，因此可以使用HAVING子句

SELECT ORDER#, SUM(PAIDEACH * QUANTITY) AS TOTAL 
  FROM ORDERITEMS 
 GROUP BY ORDER# 
HAVING SUM(PAIDEACH * QUANTITY) > 39.9
 ORDER BY TOTAL DESC; 

Answer 2

如果要在WHERE子句中使用别名，则可以将查询放在另一个中SELECT：

SELECT *
FROM
(
    SELECT ORDER#, SUM(PAIDEACH * QUANTITY) AS TOTAL 
    FROM ORDERITEMS 
    GROUP BY ORDER# 
) x
WHERE x.TOTAL > 39.9 
ORDER BY x.TOTAL DESC;

Answer 3

order by 2 desc（对列的数字引用以 1 开头）

无需编写嵌套查询，甚至无需为查询having添加子句。只需用数字引用列，但不要忘记在更改查询时更改它;-)