How to write a query that acces table only once

Hi everyone,

Lets say I have this table (table A):

PK	COL_1	COL_2
1	A	1
2	B	1
3	C	2
4	A	3
5	D	3
6	E	3

When I query this table I know the col_1 value (but I do not know the col_2 value) so I can have this WHERE clause:

SELECT *

FROM A

WHERE COL_1 = 'A';

But what I really want, is all the rows that have the same col_2 value as the col_2 values of the rows WHERE col_1='A'.

Normally to do that I would have a query with a join between table A and itself, as such :.

SELECT a1.* FROM
a a1 INNER