Question

最终SQL考试的练习题。列出收集总额（罚款和费用）以及犯罪分类所拥有的总金额。

这是我的代码。请告诉我它为什么不起作用。

select classification, fine_amount+court_fee as "collections amount", fine_amount - amount_paid as "Amount owned"
from crime_charges join crimes using (crime_id)
group by classification;

抛出错误：

ORA-00979: not a GROUP BY expression
00979. 00000 -  "not a GROUP BY expression"
*Cause:    
*Action:
Error at Line: 1 Column: 23

Answer 1

试试这个：

SELECT classification, SUM(fine_amount+court_fee) AS "collections amount", 
       SUM(fine_amount - amount_paid) AS "Amount owned"
FROM crime_charges 
INNER JOIN crimes USING (crime_id)
GROUP BY classification;

Answer 2

您必须将select子句中的所有列放入group by子句中。

Answer 3

尝试此查询：

select classification, fine_amount+court_fee as "collections amount", fine_amount - amount_paid as "Amount owned"
from crime_charges join crimes using (crime_id)
group by classification,fine_amount,court_fee,amount_paid;

Answer 4

@shabeer，感谢您对学习的兴趣。但是，将理论学习投入时间总是明智的。你的问题非常重要。使用group by的选择查询只能包含聚合函数和select子句中的列。试想一下，当您已经使用fine_amount列对dataa进行分组时，数据库如何知道选择classification列的单个值。它可能是max，min，sum等等。不是我的建议，但我只是觉得，当你开始了解基础知识时，你会感受到不同。当您在互联网上搜索解决方案时，它可能会成为一种习惯！

一切顺利！

分组将不会在我的声明中工作。为什么

4 个答案: