Compare a column itself to check whether it have duplicated value in EXCEL

Question

Suppose I have a column called item code as below:

-----  ------
|row|  |code|
-----  ------
|1  |  |A123|
-----  ------
|2  |  |B123|
-----  ------
|...|  |....|
-----  ------
|n  |  |A123|
-----  ------

The value in the column of code may appear more then one time, how can I use Excel formula or any method in Excel to check the duplicated record in a column?

Thanks

Answer 1

Depending upon which version of Excel you are using, you may be able to achieve this with Conditional Formatting.

Excel 2007 has quick 3 click setup, for conditional formatting duplicates.

Update to include instructions from xQbert below:

Quick formatting

• Select one or more cells in a range, table, or PivotTable report.
• On the Home tab, in the Style group, click the arrow next to Conditional Formatting, and then click Highlight Cells Rules.
• Select Duplicate Values. Enter the values that you want to use, and then select a format.