MySQL 8.0

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CREATE TABLE CUSTOMER
AS
SELECT 'Juan' as name,   'New York' AS city
UNION ALL SELECT 'Louis',  'Madrid'
CREATE TABLE ASESOR
AS
SELECT 'Michael' AS name,   'New York' AS city
UNION ALL SELECT 'Peter',    'Zurich'
UNION ALL SELECT 'Dan',   'Madrid'
SELECT name , city
FROM CUSTOMER c
WHERE EXISTS (SELECT 1 FROM ASESOR a WHERE c.city= a.city)
UNION ALL
SELECT name , city
FROM ASESOR a
WHERE EXISTS (SELECT 1 FROM CUSTOMER c WHERE c.city= a.city)


name
city


Juan
New York

Louis
Madrid

Michael
New York

Dan
Madrid