Use Date if Exists

I have tables A and B. Table A contains dates for all rows, but I need to use table B dates if they exist for matching rows in Table A.

I need to select all rows in Table A and replace the dates that exist in Table B for matching rows only. So, in the data below I would want to return 3 rows but the date for order 1234 needs to be from Table B (6/26/2013). Thanks in advance, skip.

Table A

Table B