The first point that comes to mind is the "Currency". In Table B (Or Bo_B), you have 3 STATIC currency Attributes (USD, EUR and GBR).
Q) Are these 3 values (USD, EUR and GBR) static values in Tabla A as well? Another words, users only have these 3 values to select? If yes, then it very simple to do.
If those values in Table A is dynamic , then it gets more difficult to do when you have STATIC attributes in Table B.
Secondly, you should have your Table A sorted by:
Date
Currency
When looping through.