what are the companies that produce the most expensive furniture | Do you mean the names of manufacturers that produce the most expensive furniture? | yes, the names of the company that produces the most expensive furniture
SELECT t1.name FROM manufacturer AS t1 JOIN furniture_manufacte AS t2 ON t1.manufacturer_id   =   t2.manufacturer_id ORDER BY t2.Price_in_Dollar DESC LIMIT 1
most expensive furniture refers to MAX(Price_in_Dollar); names of the company refers to SELECT t1.name;