sql - Double/Random alias name in select clause on Oracle 11g does not throw invalid identifier exception -

yesterday stumbled upon strange behavior on customers oracle 10g instance. procedure wrote gave me invalid identifier exception running fine on oracle 11g instances.

the relevant query following:

select b.b.v_col_b  tbla left join tblb b on a.pk_col_a = b.fk_a; 

pleas note b.b.v_col_b part of query. changing left join inner join did raise ora-00904: "b"."b"."v_col_b": invalid identifier exception, but:

1. isn't syntax error?
2. can explain behaviour?

a working demo can found on sqlfiddle

edit: added table definition:

create table tbla (   pk_col_a int primary key,    v_col_a varchar2(50));  create table tblb (   pk_col_b int primary key,    fk_a int,    v_col_b varchar2(50)); 

edit2: @lalitkumarb's mentioned seems happen on oracle 11g

congratulations, have found bug :)

in particular case can write whatever want when selecting of tblb columns:

select helloworld.b.v_col_b, mghjfghj.b.fk_a, asdasdas.b.pk_col_b tbla left join tblb b on a.pk_col_a = b.fk_a; 

you can right join:

select helloworld.b.v_col_b, mghjfghj.b.fk_a, asdasdas.b.pk_col_b tblb b right join tbla on a.pk_col_a = b.fk_a; 

it won't work oracle join syntax ( (+) notation ) though.

it not expected behaviour and, lalit noted in comments, fixed in 12c. can file bug request wit oracle support if want. maybe there patch it.