How to scaffold an existing SQL Server database using Entity Framework Core (EF Core) C#

        How to scaffold an existing SQL Server database using Entity Framework Core

To scaffold an existing SQL Server database using Entity Framework Core (EF Core) in a Database-First approach, you can use the Scaffold-DbContext command in the Package Manager Console or dotnet CLI. This process will generate the entity models and the DbContext class based on your existing database schema. Prerequisites Install .NET SDK: Make sure you have the .NET SDK installed on your machine. Install Entity Framework Core Tools: Ensure that your project has EF Core and related packages. 

Step 1: Install EF Core NuGet Packages 

In the Package Manager Console (in Visual Studio): Install-Package Microsoft.EntityFrameworkCore.SqlServer Install-Package Microsoft.EntityFrameworkCore.Tools

Step 2: Scaffold the Database

Using Package Manager Console

1. Open Package Manager Console in Visual Studio (Tools > NuGet Package Manager > Package Manager Console).
2. Run the following command:

   Scaffold-DbContext "Server=YourServerName;Database=SimpleDB;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models -Context SimpleDbContext

Step 3: Review the Generated Code

The scaffolding command will generate:

• SimpleDbContext.cs: Represents your database context.
• Entity Classes (e.g., Employees.cs): Represents your database tables as C# classes.

Example of SimpleDbContext.cs

using Microsoft.EntityFrameworkCore;

namespace YourNamespace.Models

{

    public partial class SimpleDbContext : DbContext

    {

        public SimpleDbContext(DbContextOptions<SimpleDbContext> options) : base(options) { }

        public virtual DbSet<Employee> Employees { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)

        {

            modelBuilder.Entity<Employee>(entity =>

            {

                entity.HasKey(e => e.EmployeeID);

                entity.Property(e => e.FirstName).HasMaxLength(50);

                entity.Property(e => e.LastName).HasMaxLength(50);

                entity.Property(e => e.Email).HasMaxLength(100);

                entity.Property(e => e.PhoneNumber).HasMaxLength(20);

                entity.Property(e => e.Salary).HasColumnType("decimal(10, 2)");

            });

        }

    }

}

Step 4: Update appsettings.json

{

  "ConnectionStrings": {

    "SimpleDbContext": "Server=YourServerName;Database=SimpleDB;Trusted_Connection=True;"

  }

}

Step 5: Configure Startup.cs or Program.cs

In .NET 6+, add the following in your Program.cs file:

using Microsoft.EntityFrameworkCore;

using YourNamespace.Models;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddDbContext<SimpleDbContext>(options => options.UseSqlServer(builder.Configuration.GetConnectionString("SimpleDbContext")));

var app = builder.Build();

// Configure the HTTP request pipeline.

app.Run();