Need help in getting the logic to be included in python sample code

Need help in logic :I have got two df1 and df2 which has a field key contains multiple rows)

if the key match in both data frames then I need to calculate the field Qualified.Qualified =

CASE WHEN Timesheet Date >=Date Start && Timesheet Date <= Date End Comments contains "L" then "Learner"

     WHEN Timesheet Date >= Date Start && Timesheet Date <= Date Expiry then "Qualified"     WHEN Timesheet Date >=Date End && Date Expiry = null then "Not Qualified"     WHEN Timesheet Date < Date Start then "Learner"

I am tried the below code , but unable to resolve:

import pandas as pdimport numpy as npimport osimport datetime df1 = pd.read_excel(r'C:\Users\sbhadra\AppData\Local\Programs\Python Scripts\Excel\data.xlsx')df2 = pd.read_excel(r'C:\Users\sbhadra\AppData\Local\Programs\Python Scripts\Excel\Q.xlsx')df1 = df1[['Key','Employee Code','Skill Code','Timesheet Date','Qualified']]df1['Timesheet Date']=df1['Timesheet Date'].astype('datetime64[ns]')df2 = df2[['Key','Employee Code','Qualification ID','Date Start','Date End','Date Expiry','Comments','Skill Level','Skill Qualified']]df2['Qualification ID']=df2['Qualification ID'].fillna(-1)df2['Qualification ID']=df2['Qualification ID'].astype(int)df2['Date Start']=df2['Date Start'].astype('datetime64[ns]')df2['Date End']=df2['Date End'].astype('datetime64[ns]') df2['Date Expiry']=df2['Date Expiry'].astype('datetime64[ns]')     df1['Qualified']=df1['Qualified'].astype(str) for i in df2.index:    if(pd.isnull(df2.at[i, 'Date End'])):        df2.at[i, 'Date End'] = df2.at[i, 'Date Start']for i in df1.index:    for j in df2.index:        if(df2.at[j, 'Key'] == df1.at[i, 'Key']):            if(df1.at[i, 'Timesheet Date'] >= df2.at[i, 'Date Start'] and df1.at[i, 'Timesheet Date'] <= df2.at[i, 'Date Start']):                df1.at[i, 'Qualified'] = 'Learner'        print(i,df1.at[i, 'Employee Code'],df1.at[i, 'Skill Code'],df1.at[i, 'Timesheet Date'],df2.at[i, 'Date Start'],df2.at[i, 'Date End'],df2.at[i, 'Date Expiry'])

Please find the path for the code;https://github.com/suvechha/python/blob/main/Test.py

Any help is appreciated.Thanks

The DSR table that is df1 should only populate:enter image description here