public class ApplicationDbContext : DbContext
{
    public ApplicationDbContext(DbContextOptions options) : base(options)
    {
    }
}

var connectionString = Configuration["ConnectionStrings:BookstoreDBConnectionString"];
services.AddDbContext<ApplicationDbContext>(o => o.UseSqlServer(connectionString));

"ConnectionStrings": {
	"BookstoreDBConnectionString": "Server=DESKTOP-ME7EDVE;Database=BookstoreApiDb;Trusted_Connection=True;MultipleActiveResultSets=true"
}