How come user get ora_1536: space quota exceeded for tablespace 'SYSTEM', though I never give them quota on system tablespace. The following is the query:

insert into
tpub.sgml_proc
(
sgml_proc_id,
proc_title_id,
content_id,
lan
)
select
'n306802',
'3963',
'170083',
lan
from
tpub.language_codes
/
tpub.sgml_proc
*
ERROR at line 2:
ORA-01536: space quota exceeded for tablespace 'SYSTEM'


Thank you!