Easiest way to enter items with sizes

I am new to inventory programs please help.
We are a clothing company most of our over 1000 products have sizes  such as s m l xl etc some have sizes from 28 to 46 . As i understand it this system requires me to input each style /size per line so it would look like
sku        qty
hat01-s    1
hat01-m    3
hat01-l    2

this may work  for inventory but is cumbersome for small orders that include all sizes per each style in different quantities.
Is there  a way of inputing a customer order like this ?
sku        s    m    l    x
hat01    2    1    7    3

or bringing up all sizes of a style with one click instead of cherry picking each size at a time. You can see how diffcult this would be with items that have sizes from 28 to 46