AVG（）正在复制存储在行中的数据，但未提供该列的平均值

Question

我创建了一个查询以从多个列中检索数据。 但是，当使用AVG（*）AVERAGE显示给定列的值时，该函数仅复制并显示每一行中的数据。 我本质上是希望表显示查询中的每一列，并在每一行中显示表的平均值。

如果select语句中没有多个列，则可以查询表以显示给定列的真实平均值。 我尝试使用UNION和SELF JOIN来查询AVG（*）AVERAGE，但是没有运气。

CREATE TABLE INVOICE
(
    INV_NUM NUMBER NOT NULL PRIMARY KEY,
    CUST_NUM NUMBER NOT NULL REFERENCES CUSTOMER(CUST_NUM),
    INV_DATE DATE NOT NULL,
    INV_AMOUNT NUMBER NOT NULL
);


INSERT ALL
INTO (INV_NUM,CUST_NUM,INV_DATE,INV_AMOUNT) 
VALUES ('8000','1000','3/23/2014','235.89')


INTO (INV_NUM,CUST_NUM,INV_DATE,INV_AMOUNT) 
VALUES ('8001','1001','3/23/2014','312.82')


INTO (INV_NUM,CUST_NUM,INV_DATE,INV_AMOUNT) 
VALUES ('8002','1002','3/30/2014','528.10')       


INTO (INV_NUM,CUST_NUM,INV_DATE,INV_AMOUNT) 
VALUES ('8003','1003','4/12/2014','194.78')


INTO (INV_NUM,CUST_NUM,INV_DATE,INV_AMOUNT) 
VALUES ('8004','1004','4/23/2014','619.44')

SELECT * FROM DUAL;

--------------TABLE QUERIES----------------

SELECT INV_NUM, INV_AMOUNT, AVG(INV_AMOUNT) AVERAGE, 
AVG(INV_AMOUNT)-INV_AMOUNT DIFFERENCE
FROM INVOICE
GROUP BY INV_NUM, INV_AMOUNT;

Answer 1

像这样：

with invoice as (
select 
8000 INV_NUM,1000 CUST_NUM,'3/23/2014' INV_DATE,235.89 INV_AMOUNT
from dual union all
select 8001,1001,'3/23/2014',312.82
from dual union all
select 8002,1002,'3/30/2014',528.10
from dual union all
select 8003,1003,'4/12/2014',194.78
from dual union all
select 8004,1004,'4/23/2014',619.44 from dual)
SELECT INV_NUM, INV_AMOUNT, AVERAGE, 
AVERAGE-INV_AMOUNT DIFFERENCE
FROM INVOICE,(select avg(inv_amount) average from invoice)
ORDER BY INV_NUM, INV_AMOUNT

Answer 2

您正在按INV_NUM和INV_AMT进行聚合，因此您根本没有进行任何聚合。

我认为您想要一个分析功能而不是聚合：

SELECT INV_NUM, INV_AMOUNT,
       AVG(INV_AMOUNT) OVER () as AVERAGE, 
       (AVG(INV_AMOUNT) OVER () - INV_AMOUNT) as DIFFERENCE
FROM INVOICE;