I have the following two tables;

mysql> select * from challenge;
+----+--------+-------------+--------+------+---------+--------------+
| ID | PLR_ID | ACC_TYPE_ID | season | year | CHAR_ID |
+----+--------+-------------+--------+------+---------+--------------+
| 1 | 1 | 1 | Fall | 2015 | 1175
|
| 2 | 1 | 4 | Fall | 2015 | 1175
|
| 3 | 1 | 3 | Fall | 2015 | 1175
|
| 4 | 1 | 10 | Fall | 2015 | 1175 |
| 5 | 1 | 13 | Fall | 2015 | 1175 |
| 6 | 1 | 2 | Fall | 2015 | 1175
|
+----+----------+----------------------+--------+-------+-------------+
6 rows in set (0.00 sec)

mysql> select * from patrocinio;
+----+------------+---------------+-------------+
| ID | PTRN_ID | CHLNG_ID | AMOUNT |
+----+------------+---------------+-------------+
| 1 | 1 | 1 | 1.00 |
| 2 | 4 | 3 | 2.00 |
| 3 | 3 | 6 | 1.00 |
+----+-----------+-----------------+------------+
I would like to select all rows from challenges which are NOT linked to a
patrocinio with the PTRN_ID -- which would be rows 2 through 6 of
challenges.

I am trying to go about this with a LEFT JOIN query but it does not seem to
be working for me.

mysql> select c.ID FROM challenge c LEFT JOIN patrocinio p ON
c.ID=p.CHLNG_ID WHERE p.PTRN_ID!=1;
Empty set (0.00 sec)

Instead of getting rows 2 through 6 of challenges I get no rows.

Any help on how to correctly do this query would be greatly appreciated.

Thanks