Why is SQL query returning empty?

Question

SQL

There is a table - products in which there are many products
I request the highest model number Printer

select model, type
from product
where type = 'Printer' and model=(select max(model) from product)

but the query returns 0 rows, why is that?

Answer 1

select type, max(model)
from product
group by type

Answer 2

At you model is a number? The aggregate function max only applies to numbers. What does the select max(model) from product
query return to you?

Answer 3

You have the maximum model selected among all products: and it may not be a printer. And then you look for a printer with just that model. Apparently there is no such thing. select max(model) from product