Duplicate data entry

[AL_Shaikh_Real_]

# Hi Everyone,

I badly need help.

I want to make sure that no duplicate data entry occurs

The fields in each row are as follows: (State, City, House Number)

Example

State	City	House Number	Duplicate (y/n)
Dhofar	Salalah	234	N
Dhofar	Hafa	234	N
Dakhiliyah	Salalah	234	N
Dhofar	Salalah	234	Y ( Duplicate)