如何在Oracle查询中显示聚合值和分类值？

Question

I have a simple table in Oracle that I want to group a certain way: I want to display disaggregated results alongside aggregated results in the same row. Here is the input table:

with abc as
(
    select 'aaa' nnn, 100 amt from dual union
    select 'aaa', 20 from dual union
    select 'aaa', 3 from dual union
    select 'bbb', 44 from dual
)    
select * from abc

I want to display each individual row joined with a sum of the AMT column grouped by the NNN column. I don't know how to explain this, so here's what it'd look like:

The Sum column in a given row will equal the sum of the values of the AMT column for all of the rows with an NNN value equal to the NNN value in the same given row.

I can do this by joining the input table with a grouped version of itself using the query below, but I think this is messy. My question is: Is there a builtin function in Oracle that accomplishes this? (My Oracle experience is a little weak, although I have lots of experience with SQL Server.)

with abc as
(
    select 'aaa' nnn, 100 amt from dual union
    select 'aaa', 20 from dual union
    select 'aaa', 3 from dual union
    select 'bbb', 44 from dual
)
select tblLeft.nnn, tblLeft.amt, tblRight.amtSum
from
(
    select nnn, amt from abc
) tblLeft
inner join
(
    select nnn, sum(amt) amtSum
    from abc
    group by nnn
) tblRight on tblLeft.nnn = tblRight.nnn

Answer 1

You could use analytic function to achieve your goal:

with abc as
(
    select 'aaa' nnn, 100 amt from dual union
    select 'aaa', 20 from dual union
    select 'aaa', 3 from dual union
    select 'bbb', 44 from dual
)    
select nnn,
       amt,
       sum(amt) over (partition by nnn)
  from abc;

Output:

NNN     AMT     SUM(AMT)OVER(PARTITIONBYNNN)
aaa     3       123
aaa     20      123
aaa     100     123
bbb     44      44

What analytic functions do: they allow you to use functions like SUM , but they calculate the value for each row instead of aggregating the result. They have some other interesting options, if you would like to learn more:

https://oracle-base.com/articles/misc/analytic-functions

SQLFiddle example