Tentar:
select t1.*
from orders t1
join (
select max(close) as close
from orders
group by date(close)
) t2 on t1.close = t2.close
Exemplo de trabalho:http://sqlfiddle.com/#!2/e799a/1
select t1.*
from orders t1
join (
select max(close) as close
from orders
group by date(close)
) t2 on t1.close = t2.close
