how to join 2 column data in one pandas code example

Example 1: how to merge two pandas dataframes on a column

import pandas as pd
T1 = pd.merge(T1, T2, on=T1.index, how='outer')

Example 2: how to join two dataframe in pandas based on two column

merged_df = left_df.merge(right_df, how='inner', left_on=["A", "B"], right_on=["A2","B2"])