How to calculate average of a column and then include it in a select query in oracle?

Question

My table is--

create table mobile
(
  id integer,
  m_name  varchar(20),
  cost integer
)

and the values are --

insert into         


        

Answer 1

One of the rare times a CROSS JOIN is applicable:

WITH avgcost as (select round(avg(cost)) as Average from mobile)
SELECT id, m_name as "Mobile Name", cost as Price, Average,
cost-Average as Difference
FROM mobile cross join avgcost

Which will result in:

ID  Mobile Name PRICE   AVERAGE DIFFERENCE
10  NOkia       100     123     -23
11  Samsung     150     123     27
12  Sony        120     123     -3