Oracle: DBA_DOMAIN_COLS

select
   dom.char_col_decl_length,
   dom.char_length,
   dom.character_set_name,
   dom.collation,
   dom.column_id,
   dom.column_name,
   dom.data_default,
   dom.data_length,
   dom.data_precision,
   dom.data_scale,
   dom.data_type,
   dom.data_type_id,
   dom.default_length,
   dom.default_on_null,
   dom.default_on_null_upd,
   dom.discriminant,
   dom.domain_name,
   dom.exact,
   dom.nullable,
   dom.owner
from
   dba_domain_cols dom;