ORA-00945: specified clustered column does not exist

Question

here's the code with the cluster included, the table never gets created and oracle documentation is ass

create cluster c123 (a integer)
size 512;
/

drop table t123;
/

create table t123
cluster c123 (b)
as SELECT t1.col1 FROM T1, T2, T3
WHERE T1.col1=T3.col11 AND
T2.col1=T3.col12 AND T1.col2=1;
/

it needs to create the table, instead i keep getting

...
Error report -
ORA-00945: specified clustered column does not exist
00945. 00000 -  "specified clustered column does not exist"
*Cause:    
*Action:

Answer 1

You could add alias:

create table t123
cluster c123 (b)
as 
SELECT t1.col1 AS b
FROM T1
JOIN T2 ON T1.col1=T2.col11
JOIN T3 ON T2.col1=T3.col12
WHERE T1.col2=1;