Help for a query with minus clause

Question

I want to write a query like this:
select a.field
from table_1 a
minus
select b.field
from table_2 b
where not exists (select 1
from table_3 c
where c.field = a.field);
Unfortunately I get:
ERROR at line 8:
ORA-00904: invalid column name
Can you help me?
Thanks!

Answer 1

Hi,
Mark1970 wrote:
I want to write a query like this:
select a.field
from table_1 a
minus
select b.field
from table_2 b
where not exists (select 1
from table_3 c
where c.field = a.field);
Unfortunately I get:
ERROR at line 8:
ORA-00904: invalid column name
Can you help me?
Thanks!Table_1 and its alias, a, are only in scope in the first branch of the query, before the keyword MINUS. The second branch, after MINUS, must be a complete self-contained query.
There are many ways to re-write the query, including:
select     a.field
from      table_1          a1
    minus
select     b.field
from     table_2          b
where      not exists      (
                       select     1
                   from      table_3     c
                   JOIN     table_1     a     ON     c.field = a.field
               );It's suspicious that the EXISTS sub-query does not depend on anything in table_2. Are you sure this is what you want to do?
If you'd like help, post a little sample data (CREATE TABLE and INSERT statements for all three tables) and the results you want from that data.