I need a formula that will count the unique text values of one column with a
specific value in another column. Here is an example:

Date Text
200811 Cat
200901 Dog
200901 Mouse
200811 Frog
200811 Cat
200901 Bird

If the date was 200811, then the unique values would be 2.
If the date was 200901, then the unique values would be 3.

Please let me know if you have any questions, thanks!