# df1 as main df and use the feild from df2 and map it into df1
df1.merge(df2,on='columnName',how='left')
pd.merge(product,customer,left_on='Product_name',right_on='Purchased_Product')
In [99]: result = left.join(right, on=['key1', 'key2'], how='inner')
pd.merge(product,customer,how='inner',left_on=['Product_ID','Seller_City'],right_on=['Product_ID','City'])
pd.merge(product,customer,on='Product_ID')
>>> df.join(other.set_index('key'), on='key')
key A B
0 K0 A0 B0
1 K1 A1 B1
2 K2 A2 B2
3 K3 A3 NaN
4 K4 A4 NaN
5 K5 A5 NaN
#https://pandas.pydata.org/docs/user_guide/merging.html
In [88]: result = left.join(right, how='inner')