Php: Get content from file and insert into mysql db, avoid insertion of data again which already got inserted
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I am getiing simple data from a txt file. Text file consist of list of countries. 
For e.g:
America
England
Africa
I am getting the content, explode it on line break and inserting into mysql. Till here, everything is going fine. Now what I actually want is that if i add two more countries in that list of txt file. So the data already got inserted should not insert again and only the two new lines should be added just.