.net数据库查询

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"
  }
}

var query = from user in dbContext.Users
            where user.Age > 18
            orderby user.LastName
            select user;

dotnet ef migrations add InitialCreate
dotnet ef database update

using Microsoft.EntityFrameworkCore;
using System.Linq;

public class User
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
}

public class ApplicationDbContext : DbContext
{
    public DbSet<User> Users { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;");
    }
}

public class UserService
{
    private readonly ApplicationDbContext _context;

    public UserService(ApplicationDbContext context)
    {
        _context = context;
    }

    public IEnumerable<User> GetUsersOver18()
    {
        return _context.Users.Where(u => u.Age > 18).OrderBy(u => u.LastName);
    }
}