order dates by A-Z given sheet is ordered by codes on different column

Column A has a set of codes sorted A-Z. Between the codes, the rows are in blank, symbolising they are the same as the code above. ie; A1=001; A2 to A5=blank; A6=002 and so on. The number of blank rows varies each time.
Column B has a set of dates the codes in A were purchased at. I need to order the dates from oldest to newest, but I can't apply the A-Z sort in the entire column, as it wouldn't bear in mind that different dates correspond to different codes in A.
Is there any way I could work round this? So far I'm making a manual selection in B and sorting it, but I have 99files to do, each with about 10k rows, so it's going to take forever to do so this way.

clarification:
A has a set of numbers and blank cells.
I want to sort the dates in B given a varying range in A from number, to next non-blank cell.