join pandas dataframe by column

1# df1 as main df and use the feild from df2 and map it into df1
2
3df1.merge(df2,on='columnName',how='left')

1df_merge_col = pd.merge(df_row, df3, on='id')
2
3df_merge_col
4

1df_outer = pd.merge(df1, df2, on='id', how='outer')
2df_inner = pd.merge(df1, df2, on='id', how='inner')

1>>> df.join(other.set_index('key'), on='key')
2  key   A    B
30  K0  A0   B0
41  K1  A1   B1
52  K2  A2   B2
63  K3  A3  NaN
74  K4  A4  NaN
85  K5  A5  NaN
9

1In [88]: result = left.join(right, how='inner')
2

1#https://pandas.pydata.org/docs/user_guide/merging.html