Question

Okay, so i’ve studied c# and asp.net long enough and would like to know how all these custom classes i created relate to the database. for example.

i have a class call Employee

public class Employee
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string EmailAddress { get; set; }
}

and i have a database with the following 4 fields:

ID
Name
EmailAddress
PhoneNumber

it seems like the custom class is my database. and in asp.net i can simple run the LINQ to SQL command on my database and get the whole schema of my class without typing out a custom class with getter and setter.

so let’s just say that now i am running a query to retrieve a list of employees. I would like to know how does my application map to my Employee class to my database?

Answer 1

by itself, it doesn’t. But add any ORM or similar, and you start to get closer. for example, LINQ-to-SQL (which I mention because it is easy to get working with Visual Studio), you typically get (given to you by the tooling) a custom “data context” class, which you use as:

using(var ctx = new MyDatabase()) {
    foreach(var emp in ctx.Employees) {
        ....
    }
}

This is generating TSQL and mapping the data to objects automatically. By default the tooling creates a separate Employee class, but you can tweak this via partial classes. This also supports inserts, data changes and deletion.

There are also tools that allow re-use of your existing domain objects; either approach can be successful – each has advantages and disadvantages.

If you only want to read data, then it is even easier; a micro-ORM such as dapper-dot-net allows you to use our type with TSQL that you write, with it handling the tedious materialisation code.