DELETE FROM X WHERE IN (..) is not deleting rows - mysql

Question

I have an issue where I'm filtering a table by a bunch of different values. There's about 30 different filters on this table and since I'm still a novice with MySQL I have it done in a stored procedure executing multiple DELETE queries from a temporary table to filter. This example is only going to show the filter that I'm having issues from, which is a DELETE FROM table WHERE value IN () query.
Here's a test Schisma:
CREATE TABLE accounts (
user_id INT(11) NOT NULL AUTO_INCREMENT,
name VARCHAR(40) NOT NULL,
PRIMARY KEY(user_id)
);
CREATE TABLE blocked (
user_id INT(11) NOT NULL,
other_id INT(11) NOT NULL,
);
INSERT INTO accounts (name) VALUES ('Chris'), ('Andy');
INSERT INTO blocked (user_id, other_id) VALUES (1, 2);
The queries create two tables: the accounts table containing two rows, and the blocked table containing one row where user_id 1 has user_id 2 blocked.
Here's the query that's causing us some problem (Please note that the queries are actually more complex than displayed, but the DELETE query is 100% the same, and the issue persists through the test example provided):
BEGIN
#user_in input is a int(11) value bassed in the CALL FUNCTION(ID).
CREATE TEMPORARY TABLE IF NOT EXISTS filtered AS (SELECT * FROM accounts);
DELETE FROM filtered WHERE user_id IN (SELECT other_id FROM blocked WHERE blocked.user_id = user_in);
SELECT * FROM filtered;
END
This query should delete the row with the user_id field of 2, as in the blocked table the only row is (1, 2).
Running the SELECT query directly providing the user_id returns the other_id of 2.
SELECT other_id FROM blocked WHERE blocked.other_id = 2;
However, the stored procedure returns both rows, instead of just one. Why?
NOTE: The above query is to show what is returned when the query SELECT other_id FROM blocked WHERE blocked.user_id = user_in, another example would be SELECT other_id FROM blocked WHERE blocked.user_id = 1 granted user_in is set to 1. Both of these queries will return a set of (2) which would make the delete query look like DELETE FROM filtered WHERE user_id IN (2). This is not working, for whatever reason.

Answer 1

To get a simple select of that users use next query
SELECT * FROM accounts WHERE accounts.user_id NOT IN (SELECT distinct blocked.other_id from blocked)
To do it with one single select without deleting rows from temporary table use next query:
BEGIN
CREATE TEMPORARY TABLE IF NOT EXISTS filtered AS (SELECT * FROM accounts WHERE accounts.user_id NOT IN (SELECT distinct blocked.other_id from blocked));
SELECT * from filtered;
END
No need for select all in temporary table first and then delete specific rows.
Hope it helps
EDIT:
I'v read the question and still a bit confused about you problem. But i checked this solution and it works perfectly so i don't understand what is problem with this. In your procedure you have
DELETE FROM filtered WHERE user_id IN (SELECT other_id FROM blocked WHERE blocked.user_id = user_in);
and after that you say that
SELECT other_id FROM blocked WHERE blocked.other_id = 2;
And i can say that blocked.other_id and blocked.user_id are two different columns.
No disrespect but amateur mistake to mix up columns. :)

Answer 2

The problem here is with this statement:
DELETE FROM filtered WHERE user_id IN (SELECT other_id FROM blocked WHERE blocked.other_id = user_id);
Try changing it to this:
DELETE FROM filtered WHERE user_id
IN (SELECT other_id FROM blocked);
Reason being that the blocked table has both a other_id and a user_id column. So where you are attempting to join out to the filtered table you are in fact comparing the other_id and user_id columns in the blocked table only. Which are not equal. So no delete happens.