MySQL 8.0

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create table table_1 (
  ID varchar(10),
  CODE varchar(10)
);

create table table_2 (
  ID varchar(10),
  CODE varchar(10)
);

insert into table_1 values 
('aa',  'r'),   
('aa',  'k'),   
('aa',  's'),      
('bb',  'r'),      
('bb',  'k'), 
('cc',  'r'),  
('dd',  'r'),      
('dd',  'k'),     
('ee',  's');    
                
insert into table_2 values 
('qq',  'r'),
('ff',  'k'),
('aa',  'r'),
('aa',  'k'),
('aa',  's'),
('bb',  'r'),
('bb',  'k'),
('bb',  's'),
('cc',  'k'),
('cc',  's');

Records: 9  Duplicates: 0  Warnings: 0



Records: 10  Duplicates: 0  Warnings: 0


SELECT *
FROM table_2 t2
WHERE EXISTS (
  SELECT 1
  FROM table_1 t1
  WHERE t2.ID = t1.ID 
        AND t2.CODE NOT IN ( SELECT CODE FROM table_1 WHERE ID = t2.ID)
)


ID
CODE


bb
s

cc
k

cc
s


SELECT *
FROM table_1
UNION ALL
SELECT ID, CODE
FROM table_2 t2
WHERE EXISTS (
  SELECT 1
  FROM table_1 t1
  WHERE t2.ID = t1.ID 
        AND t2.CODE NOT IN ( SELECT CODE FROM table_1 WHERE ID = t2.ID)
)


ID
CODE


aa
r

aa
k

aa
s

bb
r

bb
k

cc
r

dd
r

dd
k

ee
s

bb
s

cc
k

cc
s