mysql> select * from foo;
+----+------+
| id | name |
+----+------+
|  1 | foo  |
|  2 | foo1 |
|  3 | foo2 |
+----+------+
3 rows in set (0.00 sec)

mysql> insert into bar (name) VALUES ("test");
Query OK, 1 row affected (0.00 sec)

mysql> select LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                3 |
+------------------+
1 row in set (0.00 sec)

mysql> insert into foo (name) VALUES ("foo") on duplicate key update name=name;
Query OK, 0 rows affected (0.00 sec)

mysql> select LAST_INSERT_ID();
+------------------+
| LAST_INSERT_ID() |
+------------------+
|                3 |
+------------------+
1 row in set (0.00 sec)