MySQL 8.0

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

select version();


version()


8.0.30


CREATE TABLE names(name1 VARCHAR(20), name2 VARCHAR(20));

INSERT INTO names VALUES
   ('a','b'),
   ('b','a'),
   ('a','c'),
   ('a','d'),
   ('d','a'),
   ('e','a');

Records: 6  Duplicates: 0  Warnings: 0


SELECT * FROM names;


name1
name2


a
b

b
a

a
c

a
d

d
a

e
a


-- find the duplicates
SELECT 
  LEAST(name1,name2) as L,
  GREATEST(name1,name2) as G
FROM names
GROUP BY LEAST(name1,name2), GREATEST(name1,name2) 
HAVING count(*)>1;


L
G


a
b

a
d


WITH cte as (
  SELECT 
    LEAST(name1,name2) as L,
    GREATEST(name1,name2) as G
  FROM names
  GROUP BY LEAST(name1,name2), GREATEST(name1,name2) 
  HAVING count(*)>1
)
DELETE FROM names
WHERE (name2,name1) in (select * from cte
);
SELECT * FROM names;


name1
name2


a
b

a
c

a
d

e
a