MySQL 8.0

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select version();

version()

8.0.19

CREATE TABLE num
(
  num_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
  the_num INTEGER NOT NULL
);

INSERT INTO num (the_num) VALUES 
(145), (245), (345), (445), (545), (645), (745), (845), (945), (1145), (2145), 
(3145), (4145), (5145), (6145), (7145), (8145), (9145);
SELECT * FROM num;

num_id
the_num

1
145

2
245

3
345

4
445

5
545

6
645

7
745

8
845

9
945

10
1145

11
2145

12
3145

13
4145

14
5145

15
6145

16
7145

17
8145

18
9145

SET @var2 = "145,245,345";  -- if there are spaces between the integers, the
                            -- query fails!
SELECT @var2;

@var2

145,245,345

SELECT * FROM num WHERE the_num IN (@var2);

num_id
the_num

1
145

SELECT * FROM num WHERE FIND_IN_SET(the_num, @var2);

num_id
the_num

1
145

2
245

3
345

SELECT * FROM num WHERE the_num IN (145, 245, 345); -- works with spaces!

num_id
the_num

1
145

2
245

3
345

num_id	the_num
1	145
2	245
3	345
4	445
5	545
6	645
7	745
8	845
9	945
10	1145
11	2145
12	3145
13	4145
14	5145
15	6145
16	7145
17	8145
18	9145