i have 50+ schemas with similar structures with 300 tables each containing a column named 'ID'. I need to find only those columns having a value beginning with a common string...which could be 'A' through 'ZZ'
logged into the schema,
select table_name from user_tab_columns where column_name='ID';

gives me the tables I need. so i tried

select ID from (select table_name from user_tab_columns where column_name='ID');

thinking that i could merely add a where clause to get what i wanted, but I received:
ERROR at line 1:
ORA-00904: "ID": invalid identifier

SQL does not support/allow what you were attempting to do.
one way or another, 300 different SELECT statements must be used; one statement for each table.
utilize EXECUTE IMMEDIATE
or write SQL to construct the unique SELECT statements.

and I'm working on the select 'select...'
Thanks...

>and I'm working on the select 'select...'
YES!
It is somewhat brute force, but 100% effective.
I do it regularly.