1 of these 2 request apparently equivalent is not working - sql

Question

I try to understand how PIVOT table works
These 2 requests with pivot table seem equivalent:
I only write
tablename.column1, ...........column2 instead of tablename.*
You can find the requests here:
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=a5c3aacdaebe599bb050295caf3512b6
with
a as
(
select
a1.column_value a, a2.column_value b , cos(a1.r) c
from
(select column_value, rownum r from table(sys.odcinumberlist(1,2,3,4,5))) a1 ,
(select column_value, rownum r from table(sys.odcivarchar2list('a','b','a','b','a'))) a2
where
a1.r = a2.r)
select a.a,a.b,a.c from a --a.a,a.b
PIVOT
(
count(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
)
ORA-00904: "A"."C": invalid identifier
with
a as
(
select
a1.column_value a, a2.column_value b , cos(a1.r) c
from
(select column_value, rownum r from table(sys.odcinumberlist(1,2,3,4,5))) a1 ,
(select column_value, rownum r from table(sys.odcivarchar2list('a','b','a','b','a'))) a2
where
a1.r = a2.r)
select * from a
PIVOT
(
COUNT(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
)
intended result

Answer 1

When you do a PIVOT, Oracle will name the resulting columns just like their original values.
You can see this behavior when you do your select * that is working :
with
a as
(
select
a1.column_value a, a2.column_value b , cos(a1.r) c
from
(select column_value, rownum r from table(sys.odcinumberlist(1,2,3,4,5))) a1 ,
(select column_value, rownum r from table(sys.odcivarchar2list('a','b','a','b','a'))) a2
where
a1.r = a2.r)
select * from a
PIVOT
(
COUNT(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
)
result is
C 'a' 'b'
-.65364362086361191463916818309775038145 0 1
.5403023058681397174009366074429766037354 1 0
-.98999249660044545727157279473126130238 1 0
.2836621854632262644666391715135573083265 1 0
-.41614683654714238699756822950076218977 0 1
Your columns headings have been turned by Oracle into the exact values you've got in the IN clause, including the surrounding quotes.
So to refer them in your SELECT clause, you should use double quotes like this:
select "'a'","'b'", c from a
PIVOT
(
count(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
)
An alternative is to alias your values directly in the IN clause
select val_a, val_b, c from a --a.a,a.b
PIVOT
(
count(a.a)--,sum(a.c)
FOR b IN ('a' val_a, 'b' val_b )
)
VAL_A VAL_B C
0 1 -.65364362086361191463916818309775038145
1 0 .5403023058681397174009366074429766037354
1 0 -.98999249660044545727157279473126130238
1 0 .2836621854632262644666391715135573083265
0 1 -.41614683654714238699756822950076218977
And finally, you had another mistake in your initial approach:
select a.a,a.b,a.c from a --a.a,a.b
PIVOT
(
count(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
)
in this query a refers to your initial a CTE. When you do a.a,a.b,a.c, Oracle doesn't know what you are referencing because of the PIVOT that comes afterwards.
You should properly alias the PIVOT results if you want to refer to it in the SELECT clause :
select pa."'a'",pa."'b'", pa.c from a
PIVOT
(
count(a.a)--,sum(a.c)
FOR b IN ('a', 'b')
) pa