MySQL 8.0

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Create Table table_name(id INT, source INT);

Insert Into table_name Values(1,10),
(1,20),
(1,30),
(2,10),
(2,20),
(2,30),
(3,10),
(3,20);

Records: 8  Duplicates: 0  Warnings: 0


SELECT source, COUNT(DISTINCT id) FROM
table_name
GROUP BY source
HAVING COUNT(DISTINCT id)=(SELECT COUNT(DISTINCT id) FROM table_name)


source
COUNT(DISTINCT id)


10
3

20
3


CREATE PROCEDURE getSourceWithAllIds() 
   BEGIN
   SELECT source FROM
   table_name
   GROUP BY source
   HAVING COUNT(DISTINCT id)=(SELECT COUNT(DISTINCT id) FROM table_name);
   END 

call getSourceWithAllIds();


source


10

20