MySQL Deleting based upon a query result - mysql

Question

I have the following mysql query which finds the most recently modified and unique spawnpoint_id from a pokemon table in my database:
SELECT
t1.spawnpoint_id, t1.last_modified
FROM
pokemon t1
INNER JOIN
(SELECT
MAX(last_modified) last_modified, spawnpoint_id
FROM
pokemon
GROUP BY spawnpoint_id) t2 ON
t1.spawnpoint_id = t2.spawnpoint_id
AND t1.last_modified = t2.last_modified;
I get the results I want with the above.... but now, I want to delete all records that don't match these results.
I have tried to enclose the query in a DELETE .. NOT IN something like this:
DELETE FROM pokemon WHERE (spawnpoint_id, last_modified) NOT IN (
SELECT
t1.spawnpoint_id, t1.last_modified
FROM
pokemon t1
INNER JOIN
(SELECT
MAX(last_modified) last_modified, spawnpoint_id
FROM
pokemon
GROUP BY spawnpoint_id) t2 ON
t1.spawnpoint_id = t2.spawnpoint_id
AND t1.last_modified = t2.last_modified) x;
but I'm getting MySQL syntax error. I've been searching for a couple of hours, and finally hoped someone here might be able to help me discover what I'm doing wrong. Many thanks.
EDIT: SHOW CREATE TABLE pokemon;
CREATE TABLE pokemon (
encounter_id varchar(50) NOT NULL,
spawnpoint_id varchar(255) NOT NULL,
pokemon_id int(11) NOT NULL,
latitude double NOT NULL,
longitude double NOT NULL,
disappear_time datetime NOT NULL,
individual_attack int(11) DEFAULT NULL,
individual_defense int(11) DEFAULT NULL,
individual_stamina int(11) DEFAULT NULL,
move_1 int(11) DEFAULT NULL,
move_2 int(11) DEFAULT NULL,
last_modified datetime DEFAULT NULL,
time_detail int(11) NOT NULL,
PRIMARY KEY (encounter_id),
KEY pokemon_spawnpoint_id (spawnpoint_id),
KEY pokemon_pokemon_id (pokemon_id),
KEY pokemon_disappear_time (disappear_time),
KEY pokemon_last_modified (last_modified),
KEY pokemon_time_detail (time_detail),
KEY pokemon_latitude_longitude (latitude,longitude)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

Answer 1

I think the problem is that you use table pokemon, from which you want to delete rows, in the from-part of a subquery (which is not permitted).
One could get around this by first doing an update-statement that marks the rows to be deleted, and then do a separate delete statement. Note that the "must not use in the from-part"-restriction also applies to update-statements. Yet this can be solved by using a join rather than a subselect as follows:
create table a (
x int,
y int
);
insert into a (x,y) values (1,2),(3,4);
update a a1, (select max(a2.x) as x from a a2) a3 set a1.y = 0 where a1.x = a3.x;
delete from a where y=0