Actually, looks like Fabio's suggesting to open the same table in two different areas and SEEK in an area while appending in the other. This would validate the APPEND while it is being populated. Table does not need to be populated before.
Following Fabio's idea, maybe this would work as well, without having to open the table AGAIN:

SELECT targetTable
* close or delete any index
INDEX ON uniqueExpression UNIQUE TAG tag1 && actually, the tag doesn't have to be unique
APPEND FROM txtFile SDF FOR NOT INDEXSEEK(uniqueExpression, .F., "targetTable", "tag1")

HTH



>Maybe I'm just confused but it appears to me the scenario you suggest requires that the table be populated first. Otherwise I wouldn't be able to do the check. So ultimately I'd be running the append twice; once to populate the table (with the Unique index) then checking aginst the first table when appending to the second. It solves the issue of eliminating the duplicates but is basically the same as Martin's suggestion which would require me to run the append process twice, right? I still don't see how this would work in one pass. Am I missing something ?
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>This application will be replacing an old mainframe program, which by the way takes over 8 hours to run the same process, so from an operations standpoint it's still no contest as the time would be cut by 3/4 even if it takes a couple hours. It just seems to me that I should be able to do this faster (and in one pass).
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>Thanks for your help.