select
  М1.Магазин,
  М2.Магазин

from Обмен
  left join Магазин М1 on М1.ID = Обмен.Магазин1
  left join Магазин М2 on М2.ID = Обмен.Магазин2

-- Таблицы

CREATE TABLE SHOP (
ID   INTEGER NOT NULL,
NAME VARCHAR(100)
);

ALTER TABLE SHOP ADD CONSTRAINT SHOP_PK PRIMARY KEY (ID);


CREATE TABLE SHOP_EXCHANGE (
IDSHOP1 INTEGER,
IDSHOP2 INTEGER
);

ALTER TABLE SHOP_EXCHANGE ADD CONSTRAINT SHOP_EXCHANGE_FK_IDSHOP1 FOREIGN KEY (IDSHOP1) REFERENCES SHOP(ID);
ALTER TABLE SHOP_EXCHANGE ADD CONSTRAINT SHOP_EXCHANGE_FK_IDSHOP2 FOREIGN KEY (IDSHOP2) REFERENCES SHOP(ID);

-- Запрос

select
  SHOP1.NAME as SHOP1_NAME,
  SHOP2.NAME as SHOP2_NAME

from SHOP_EXCHANGE
  left join SHOP SHOP1 on (SHOP1.id = SHOP_EXCHANGE.IDSHOP1)
  left join SHOP SHOP2 on (SHOP2.id = SHOP_EXCHANGE.IDSHOP2)