public class Startup

    {

       ...

        /// <summary>

        ///

        /// </summary>

        /// <param name="services"></param>

        public void ConfigureServices(IServiceCollection services)

        {

             services.AddDbContext<service.exercise.Database.SunnyTaskContext>(options => options.UseSqlServer(Configuration.GetConnectionString("SunnyTask"), b => b.UseRowNumberForPaging()));//【临时】连接老SqlServer数据库

        }

...

    }