How to achieve dropdown and checkbox value saved and retrieved in .net

Dear team  i am currently learning .net core with mvc using .net 6 version with mysql

I am net to mvc pattern and i have difficuilty in achieving few things.

1. i need to have all common tables in db and need to fetch it in create and edit page i need to fetch the seleced value along with other values with selected value as selected value in dropdown . as of now i am using enum to do it but i want to do it in a tradicional way . also i need to raise error message id the selected value is null(in model.isvlaid )

 

2. I have a checkbox which will on check it will duplicate / copy the values in the other text box. i need to save the status of the checkbox somewhere prefereably insode db itslelf and i need to insert / update in creatre  and edit page

 

 

there are the two things i am struck at for the pastweek and did some research online and tried some solutions which was not successfull..

 

i have attaachec my repo link: github.com/dev-gurukaushik/ddandcheckbox

i kindly request somebody to please help me to achieve the following.

 

i have added the db scripts inside the repos in db script folder.

 

Please help