not really to suggest you a "direct conversion" kind of solutions as different programming languages got their own strengths and weaknesses.

I would suggest you to start with an execution master plan, which could include your whole project management, areas such as scope, cost, time, procurement, risk to undertake, etc.

Talk to the various stakeholders to know their expectations, what's the limitations, and plan how should this new system to be deployed, whether using traditional SDLC or a more agile approach.

First of all: Take a look at the requirements again. Do they imply or request a certain architecture?

If not, take a look at the different architectural approaches, which are possible in .NET and especially in web applications. These differences in comparison to a native Delphi application are much more important than learning C# / .NET.

Here I would especially think about a kind of Angular/Knockout based HTML5 front-end bound to RESTful web-services (web service). But there is also ASP.NET in its different incarnations (WebForms, MVC, etc.).

Also take a look at the Fowler's EE patterns. Where do you want to place the business logic? What about (normal) persistence vs. a clean relational data model? What kind of persistence (relationl, NoSQL)?

Each of this high level decisions or problems has much more impact (when making an error there) than learning (making errors) in C#/.NET.

As far as I see I can (or anyone can) write my Delphi program using C# .Net. Because it is basicly a database driven program with MySQL. You get information and send information. Not much more...

Hi Faith,

Please do have a look at ASP.Net Core as well. https://docs.microsoft.com/en-us/aspnet/core/?view=aspnetcore-2.1

This is the VNEXT for ASP.Net and will help you make your app a bit more future-proof.

Regards,
Chinmay.

the skills you need to port a program from Delphi to C# are much different from development of a new c# program and completely different to the task of maintaining or enhancing an existing c# program. i would recommend a tutorial of a demanding c# database sample, followed by some smaller new c# sharp projects to gain experience. in my opinion porting old projects from Delphi to C# makes only sense if you get money for it.

Sara

As far as I see I can (or anyone can) write my Delphi program using C# .Net. Because it is basicly a database driven program with MySQL. You get information and send information. Not much more...

Is this your projects starting point?

You'll have the Delphi application executable and nothing else besides do it in C#/.NET as a web application?

You need an analysis phase with your customer to gather/derive the requirements from the existing application. Simply copying the existing application must fail. Cause the a web application is fundamentally different from a executable on the client.

Does this migration/conversion includes data migration from the old system?

There are a lot of points you need to do before starting to learn C# or HTML or anything else.
But for your original question:

As long as you do it as a single person job, it's much more important to learn the client-side technologies (HTML5, CSS, JavaScript, framework usage and misusage) than learning C#. Cause C# is OO, thus as a Delphi developer you will pretty quickly learn it.
The things on the C# side, which are important to know, but are not the same as learning C# are Unit Testing, Entity Framework, Dependency Injection, logging and tracing and maybe delegated Kerberos authentication. Just to name a few things.

Just to make it clear, my application has these kinds of interfaces for information entry.

looks like a complex system for me, depends on the resources you have, you should discuss with your stakeholders what features to keep (and what to discard), and roll your new system up perhaps in different phases

you may also develop a POC (proof of concept) program in .NET and see if your end users (as what as your own development team) satisfied with it.

you may consider the pro and cons whether to keep the program in classic desktop or in web based as what already suggested above by other experts.

Take a note that your app can have same/similar functions as a web app, but whole logic need to be simplified and divide into fewer simple to use - modules. And don't need to be as you Delphi app at all.
Don't think that .Net will do the good job here... Better will be some js framework or php instead.