Thanks for your help! You help me a lot! But I still have one question, would you please explore! Maybe my question was not clear before: Let me explain details again, I have added Company FF to HH. If the Company is unique then I would like to assign it a new group no. but now all unique companies which group in one group. Data Source Company Employee AA David AA Winnie AA Tom AA Daisy BB David BB Peter CC Mary CC Peter CC Tony CC Apple DD Lemon DD Sky EE Cara EE Peter EE Susan FF Mark GG Luck HH Leon Expected Output File Format ID New_Grouping AA GP01 BB GP01 CC GP01 EE GP01 David GP01 Winnie GP01 Tom GP01 Daisy GP01 Peter GP01 Mary GP01 Tony GP01 Apple GP01 Cara GP01 Susan GP01 DD GP02 Lemon GP02 Sky GP02 Mark GP03 Luck GP04 Leon GP05
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