Question: How do I filter unique rows and sort by date?

Answer: Column A and B are the original list. Column D and E are the filtered unique list sorted by date. See picture below.

filter-unique-rows-and-sort-by-date

Array formula in D2:

=INDEX(Date, MATCH(SMALL(IF(COUNTIF(Values, Values)=1, COUNTIF(Date, "<"&Date), ""), ROWS(D1:$D$1)), IF(COUNTIF(D1:$D$1, Values)=1, 0, 1)*COUNTIF(Date, "<"&Date), 0)) + CTRL + SHIFT + ENTER

copied down as far as necessary.

Array formula in E2:

=INDEX(Values, MATCH(SMALL(IF(COUNTIF(Values, Values)=1, COUNTIF(Date, "<"&Date), ""), ROWS(E1:$E$1)), IF(COUNTIF(E1:$E$1, Values)=1, 0, 1)*COUNTIF(Date, "<"&Date), 0)) + CTRL + SHIFT + ENTER

copied down as far as necessary.

Named ranges
Date (A2:A21)
Values (B2:C21)
What is named ranges?

How to implement array formula to your workbook
Change named ranges. If your list starts at, for example, F2. Change D1:$D$1  in the above formulas to F1:$F$1 and E1:$E$1 to G1:$G$1

Download excel example file.
filter-unique-values-and-sort-by-date.xls
(Excel 97-2003 Workbook *.xls)

Functions in this article:

IF(logical_test;[value_if:true];[value_if_false])
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE

INDEX(array,row_num,[column_num])
Returns a value or reference of the cell at the intersection of a particular row and column, in a given range

SMALL(array,k) Returns the k-th smallest row number in this data set.

ROWS(array) returns the number of rows in a reference or an array

MATCH(lookup_value;lookup_array; [match_type] Returns the relative position of an item in an array that matches a specified value

INDEX(array,row_num,[column_num])
Returns a value or reference of the cell at the intersection of a particular row and column, in a given range

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given condition