in reply to undef and empty variables

If you are not using warnings, then indeed undef will be translated into "".

However you should use warnings because it will catch other things, and so should include the defined check to avoid that warning. Furthermore think carefully about your data. It could be that "" is a valid value. Therefore my natural inclination would be to keep "" as a valid value, and map undef to null.

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Re^2: undef and empty variables
by herveus (Parson) on Jan 19, 2011 at 17:15 UTC

    Depending on the RDBMS, the empty string may not be distinguished from NULL. Oracle leaps instantly to mind as one which explicitly documents their equivalence between an empty string and NULL. That's not standards compliant, but it's Oracle.

      That is one of the reasons that I said "think carefully about your data" instead of "null and empty string ar different".