Restricting a duplicate combination of entries

[mrh001]

I would like to restrict duplicate entries from being entered. My criteria for a duplicate entry is a COMBINATION of a number in Column A AND a number Column E (on the same row) is identical to a combination in Columns A and E on some other row - this is a duplicate entry and would not be allowed, however, duplicate numbers are allowed individually in either Column A or Column E. If a duplicate is detected, I would like to restrict the number from being entered as well as give the user an error message, asking the user to enter an alternate number.

Note, a blank in either <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-comffice:smarttags" /><st1:State w:st="on"><st1lace w:st="on">Column</st1lace></st1:State> A or Column E would be allowed and is not considered to form a duplicate combination.

Hope I am clear in my problem statement, if not I will try to clarify further if needed.

Any help would be appreciated, thanks in advance! <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
<o> </o>

 

[venkat1926]

This is the suggestion

in each row in an empty cell concantenate the corresponding cells in A and E

for example in row 2 in the empty cell in the same row (suppose this is K2) type this formula
=A2&E2
copy K2 down;.

now you can remove the rows with duplicates in column K. There are many references in google search;. I think in excel 2007 the provision is already there.