You need to be very careful about mixing join conditions and filtering conditions in the ON clause. Especially when doing outer joins, the results might not be the same.
The first example has the condition in the ON clause, in the second I moved it to the WHERE clause.
SQL> select * from t1;
COL1 C
-------------------- -
1 a
2 b
3 c
4 d
SQL> select * from t2;
COL1 C
-------------------- -
1 x
SQL> select *
2 from t1
3 left join t2 on (t1.col1 = t2.col1 and t2.col2 = 'xyz')
4 ;
COL1 C COL1 C
-------------------- - -------------------- -
4 d
3 c
1 a
2 b
SQL> select *
2 from t1
3 left join t2 on (t1.col1 = t2.col1)
4 where t2.col2 = 'xyz';
no rows selected
Your example is an inner join, so I think you're OK either way. Still, for consistency I always put only the join conditions in the ON clause and filtering conditions in the WHERE clause.
