要使用ASP.Net Core 3.1 Razor Pages和Dapper进行CRUD操作，您需要按照以下步骤进行设置：

1. 创建一个ASP.Net Core 3.1 Razor Pages项目。

2. 在项目中安装Dapper和Dapper.Contrib包。可以通过NuGet包管理器或通过命令行运行以下命令来安装它们：

   Install-Package Dapper
   Install-Package Dapper.Contrib
   

3. 创建一个名为Models的文件夹，并在其中创建一个名为Employee.cs的类，表示员工模型。示例代码如下：

   public class Employee
   {
       public int Id { get; set; }
       public string Name { get; set; }
       public string Email { get; set; }
       public string Department { get; set; }
   }
   

4. 在appsettings.json文件中配置数据库连接字符串。示例代码如下：

   {
     "ConnectionStrings": {
       "DefaultConnection": "your_connection_string_here"
     },
     // other configurations...
   }
   

5. 在Startup.cs文件的ConfigureServices方法中配置Dapper并注册数据库连接。示例代码如下：

   using Microsoft.Extensions.Configuration;
   using Dapper;
   using System.Data.SqlClient;
   
   public void ConfigureServices(IServiceCollection services)
   {
       // other service configurations...
   
       services.AddTransient(c =>
           new SqlConnection(Configuration.GetConnectionString("DefaultConnection")));
   }
   

6. 创建一个名为EmployeeRepository.cs的类，用于执行与数据库相关的操作。示例代码如下：

   using Dapper;
   using System.Collections.Generic;
   using System.Data;
   using System.Threading.Tasks;
   
   public class EmployeeRepository
   {
       private readonly IDbConnection _db;
   
       public EmployeeRepository(IDbConnection db)
       {
           _db = db;
       }
   
       public async Task> GetAllEmployees()
       {
           return await _db.QueryAsync("SELECT * FROM Employees");
       }
   
       public async Task GetEmployeeById(int id)
       {
           return await _db.QueryFirstOrDefaultAsync("SELECT * FROM Employees WHERE Id = @Id", new { Id = id });
       }
   
       public async Task CreateEmployee(Employee employee)
       {
           return await _db.ExecuteAsync("INSERT INTO Employees (Name, Email, Department) VALUES (@Name, @Email, @Department)", employee);
       }
   
       public async Task UpdateEmployee(Employee employee)
       {
           return await _db.ExecuteAsync("UPDATE Employees SET Name = @Name, Email = @Email, Department = @Department WHERE Id = @Id", employee);
       }
   
       public async Task DeleteEmployee(int id)
       {
           return await _db.ExecuteAsync("DELETE FROM Employees WHERE Id = @Id", new { Id = id });
       }
   }
   

7. 创建一个名为Index.cshtml的Razor页面，用于显示所有员工信息。示例代码如下：

   @page
   @model IndexModel
   @{
       ViewData["Title"] = "Employee List";
   }
   
   @ViewData["Title"]
   
   
           @foreach (var employee in Model.Employees)
           {
               
           }
       
   
       
   
           
   
               
   Id
               
   Name
               
   Email
               
   Department
           
       
       
   
                   
   @employee.Id
                   
   @employee.Name
                   
   @employee.Email
                   
   @employee.Department
               
   
   

8. 在Index.cshtml.cs文件中创建一个名为IndexModel的Razor页面模型，并在OnGet方法中获取所有员工信息。示例代码如下：

   using Microsoft.AspNetCore.Mvc.RazorPages;
   using System.Collections.Generic;
   using System.Threading.Tasks;
   
   public class IndexModel : PageModel
   {
       private readonly EmployeeRepository _employeeRepository;
   
       public IndexModel(EmployeeRepository employeeRepository)
       {
           _employeeRepository = employeeRepository;
       }
   
       public IEnumerable Employees { get; set; }
   
       public async Task OnGet()
       {
           Employees = await _employeeRepository.GetAllEmployees();
       }
   }
   

9. 运