MySQL 8.0

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create table myTable (
custId int,
orderId int );

insert into myTable values 
(12455,4070),
(12454,4070),
(12454,4077),
(12455,4077),
(12454,2659),
(12455,1928),
(12454,2012),
(12453,1354);

Records: 8  Duplicates: 0  Warnings: 0


select * from myTable;


custId
orderId


12455
4070

12454
4070

12454
4077

12455
4077

12454
2659

12455
1928

12454
2012

12453
1354


SELECT orderId
FROM myTable
WHERE custId IN (12455, 12454)
GROUP BY orderId
HAVING COUNT(DISTINCT custId) = (
    SELECT COUNT(DISTINCT custId)
    FROM myTable
    WHERE custId IN (12455, 12454)
);


orderId


4070

4077

custId	orderId
12455	4070
12454	4070
12454	4077
12455	4077
12454	2659
12455	1928
12454	2012
12453	1354