Compare multiple values to subquery result in where clause - mysql

Question

I have two related tables as follows :
USERS
user_id <\PK>
USERACTIONS
user_action_id <\PK>
user_id <\FK>
user_action <\int>
Whenever user performs an action, there is a new insertion in "useractions" table. I need a query to fetch those USERACTION rows where user performed only particular set of actions say (1,2) but not (3,4).
So I have a query like -
select * from USERACTIONS where (1,2) in(select user_action from USERACTIONS where user_id=100) and user_id=100;
Problem is the above query doesn't work as supplying (1,2) expects subquery also to return two columns which is understandable. This is the error I get -
ERROR: subquery has too few columns
Giving a single value say (1) or (2) works perfectly. I want to know if there is any way I can use the same query and compare the subquery's result with multiple values? I prefer the same query because the case demonstrated here is just a part of a large query.
Please note the query should not list users who performed (1,2,3,4) those who performed only (1,2) should be listed and also user_action values can be any random integer.
Any alternate queries are welcome but would prefer changes in the same query. Thanks in advance.

Answer 1

try this:
SELECT USERS.user_id, USERACTIONS.user_action
FROM USERACTIONS
LEFT JOIN USERS ON USERS.user_id = USERACTIONS.user_id where USERACTIONS.user_action in (1,2);

Answer 2

This Works for your query.
You add the numbers to the in Clause
SELECT a.user_id
FROM
(SELECT DISTINCT user_id
from
USERACTIONS
WHERE user_action
IN (1,2)) a
INNER JOIN
(SELECT DISTINCT user_id
from
USERACTIONS
WHERE user_action
NOT IN (1,2)) b
ON a.user_id <> b.user_id
;
CREATE TABLE USERACTIONS (id INT NOT NULL AUTO_INCREMENT
, PRIMARY KEY(id)
, user_action INT
, user_id INT
);
INSERT USERACTIONS VALUES (NULL,1,100),(NULL,2,100),(NULL,3,100), (NULL,1,101),(NULL,2,101);
✓
✓
SELECT a.user_id
FROM
(SELECT DISTINCT user_id
from
USERACTIONS
WHERE user_action
IN (1,2)) a
INNER JOIN
(SELECT DISTINCT user_id
from
USERACTIONS
WHERE user_action
NOT IN (1,2)) b
ON a.user_id <> b.user_id
;
| user_id |
| ------: |
| 101 |
db<>fiddle here

Answer 3

I see typical SO answers that aren't answering OP's question, but rather trying to steer them in a different direction. I know this is old, but if anyone stumbles upon this, I believe this will be more helpful.
I too have a large, enterprise solution where the WHERE check is MUCH more performant in a subquery than using a JOIN.
You can set a variable in your WHERE clause and use it afterwards. I am currently trying to find a better way to do this without setting a variable, but something like this works:
SELECT * FROM USERACTIONS
WHERE
( #useraction =
(select user_action from USERACTIONS where user_id=100 LIMIT 1)
= 1
OR #useraction = 2)
AND user_id=100;
What you are doing is creating a variable in your WHERE clause, setting that variable, then using it later. This is encapsulated, so it can match either one of the conditions.