The fields a first name, name, st. number, street, city, pincode,
telephone, e-mail, etc.
a "unique field" can be the e-mail, or the telephone number.
Or few fields together connected by "and" like first name "and" name, which
doesn't give 100% sure of a double record, but worth checking it manualy.

"Toppers" wrote:

How is the data organised and what field(s) can be tested for as unique?

"arad" wrote:

Hello good people.

Im having data tables with a list of records representing mailing list of
my customer.
How can I verify that every record is unique (for example: to avoid sending
two letters to the same customer)

Thanks in advance
Arad