>Why a pifall?
>
>Vlad
>
>>>Use SELECT SQL with UNION clause (it eliminates duplicates) or append everything in one table and index it UNIQUE.
>>>
>>>Vlad
>>
>>
>>UNION is ok but appending than indexing unique is a PITFALL !
>>Cetin

First, physically you'll have all duplicates and see them unique only setting order. But the second and important, any table can have many fields with different data types. To get the result you should build an expression that would set them all to the same type, if you are gonna do it next comes, the resulting expression would be likely out of limits of key expression capacities (which is 240 for compact indexes for now - you don't have much chance to fit the index).
Cetin