How to calculate birthday with sql database in core application

Question

Hi teachers I am writing dotnet core application.My application have age different calculation topic.But i am not write therefore searching google.Results is calculation formula in write model.I want user insert birthday date then save button.Then index.chtml have auto calculate example 30year,5month,27days .Please help me. I don't know.How to write and example teaching to me please .Thank for developers.