select t.table_name as table_name,
c.column_id as column_id,
c.column_name as column_name,
c.data_type as column_type,
CASE WHEN c.nullable = 'Y' THEN 1 ELSE 0 END AS is_nullable,
c.column_key,
c.extra
from sysdba.all_tables t
inner join sysdba.all_tab_columns c
on c.owner = t.owner
and c.table_name = t.table_name
where t.table_type = 'BASE TABLE'
and t.owner = current_user
order by t.table_name,
c.column_id;
这么写这个语句就是查不出来，我需要怎么改才可以你呢，有没有什么文档参考