Oracle :

select distinct object_type from user_objects

SELECT table_schema,table_name
FROM information_schema.tables
ORDER BY table_schema,table_name;


PostgreSQL :

List of objects in a schema ( equivalent to Oracle user Scott of employee db)

select nsp.nspname as object_schema,
cls.relname as object_name,
rol.rolname as owner,
case cls.relkind
when 'r' then 'TABLE'
when 'i' then 'INDEX'
when 'S' then 'SEQUENCE'
when 'v' then 'VIEW'
when 'c' then 'TYPE'
else cls.relkind::text
end as object_type
from pg_class cls
join pg_roles rol on rol.oid = cls.relowner
join pg_namespace nsp on nsp.oid = cls.relnamespace
where nsp.nspname not in ('information_schema', 'pg_catalog')
and nsp.nspname not like 'pg_toast%'
and rol.rolname = current_user
order by nsp.nspname, cls.relname;