要实现显示每个月/年类别的费用总计行和每月总费用，您可以按照以下步骤进行操作：

1. 创建一个ASP.Net Core MVC项目。

2. 安装所需的NuGet包：

   • Microsoft.EntityFrameworkCore
   • Microsoft.EntityFrameworkCore.SqlServer

3. 创建一个表示费用的实体类：

public class Expense
{
    public int Id { get; set; }
    public string Category { get; set; }
    public decimal Amount { get; set; }
    public DateTime Date { get; set; }
}

4. 创建一个表示数据库上下文的类：

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

    public DbSet Expenses { get; set; }
}

5. 在Startup.cs文件中添加数据库上下文的配置：

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddControllersWithViews();
}

6. 创建一个控制器类，用于处理费用相关的操作：

public class ExpenseController : Controller
{
    private readonly ExpenseContext _context;

    public ExpenseController(ExpenseContext context)
    {
        _context = context;
    }

    public IActionResult Index()
    {
        var monthlyTotal = _context.Expenses
            .GroupBy(e => new { e.Category, e.Date.Year, e.Date.Month })
            .Select(g => new
            {
                Category = g.Key.Category,
                Year = g.Key.Year,
                Month = g.Key.Month,
                Total = g.Sum(e => e.Amount)
            })
            .OrderBy(g => g.Year)
            .ThenBy(g => g.Month)
            .ToList();

        var yearlyTotal = _context.Expenses
            .GroupBy(e => new { e.Category, e.Date.Year })
            .Select(g => new
            {
                Category = g.Key.Category,
                Year = g.Key.Year,
                Total = g.Sum(e => e.Amount)
            })
            .OrderBy(g => g.Year)
            .ToList();

        ViewBag.MonthlyTotal = monthlyTotal;
        ViewBag.YearlyTotal = yearlyTotal;

        return View();
    }
}

7. 创建一个Razor视图来显示费用总计行和每月总费用：

@model IEnumerable

Monthly Total

        @foreach (var item in Model)
        {
            
        }
    

    

        

            
Category
            
Year
            
Month
            
Total
        
    
    

                
@item.Category
                
@item.Year
                
@item.Month
                
@item.Total
            


Yearly Total

        @foreach (var item in ViewBag.YearlyTotal)
        {
            
        }
    

    

        

            
Category
            
Year
            
Total
        
    
    

                
@item.Category
                
@item.Year
                
@item.Total
            

以上代码将从数据库中检索费用数据，并使用efcore执行分组和求和操作，然后将结果传递给Razor视图进行显示。在视图中，您可以使用循环来遍历结果并在表格中显示数据。