How to format a cell based on the the cell above it?

I have a list of dates in ascending order, with quite a few duplicates, and I want to bold the first one of every unique date. (e.g. May 1st, May 1st, May 2nd, May 3rd, May 3rd)

I wanted to bold another column based on the last unique one in this one and was able to achieve it after a little research by simply using the formula =$A1 < $A2. That idea doesn't seem to work here though as =$A1 > $A0 gives an error message. How do you do this?

Edit: I'm using 开发者_运维问答Excel 2007.

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Assume the dates are contained in the cells A2, A3, A4... (due to the nature of the formula we need a header line and thus A1 is not in the range). The column you want to format is column B.

• select cells B2 to B?
• capture conditional formatting with formula =$A2<>$A1

Now only the first unique line (based on criterion in column A) is formatted differently.

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If you're using Excel 2007, you can use Conditional Formatting (a style button off of the Home tab).

• Select the dates as a range.
• Conditional Formatting -> New Rules.
• Choose "Format only unique or duplicate values"
• Format all pulldown: Choose "duplicate" values in the selected range.
• On the Font tab, Select Bold under Font style.
• Press OK twice.

This will bold all of the duplicated dates.

EDIT: OP really wants the first of all unique values. Here is a way to do that (without an extra column).

• Select the second date (A2)
• Conditional Formatting -> New Rules.
• Choose "Use a formula to determine which cells to format"
• Enter formula =$A2<>$A1 . The dollar signs are important.
• On the Font tab, Select Bold under Font style.
• Press OK twice.
• Use the format painter to copy the Conditional Formatting from A2 to the last date.
• Format A1 as bold, as it will always be unique.

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An alternate approach is to use the following for the Conditional Formatting formula:

(A1<>INDIRECT(ADDRESS(CELL("row")-1,CELL("col"),1)))