Add validation to check if the user has already made a loan?

Question

Add validation to check if the user has already made a loan payment.

 

When the user fills in all the fields and hits submit, the logic will check if there is already an entry on the same day with the same details in the database.

 

If yes, we will show the message and a check box to confirm if the user wants to submit even if it’s a duplicate.

 

please give me answer with asp page and c#.