float comparison?

[Jerry Swanson]

Why when I do select from database and try to compare float field with float
number, I have no results

amount --- type float

select * from price where amount = 3.45 // doesn't work
select * from price where amount = '3.45' //doesn't work

select * from price where amoun like '3.45' //work

My question is how to compare float field with float number. What operator I
should use?