Record already exist error while importing .csv file

How to handle the “record already exist error” while importing records from .csv file to table in ax 2012.
I am using commaIO class for importing data into table


The error indicates that there is a violation of primary index key. Therefore you should add code to check and prevent this violation

Not sure what you are importing. If you give more info on your import, we will be able to help you.

Thanks for the reply,

I have a table (CustDetails) with three fields. In that CustNO is primary key (Unique) And already some record present in CustDetails table. While importing .CSV IF CustNO already Exist then it should update other TWO fields else all three fields should be imported into the table

You need to find the existence of the record, if the record exists then you need to update the record(by selecting the record forupdate) or else you need to insert the record.