如何使用Linq显示多个表中的数据。 [英] How Do I Display Data From More Than One Table Using Linq.

问题描述

我有以下型号和表格

  public   class 学生
 {
  public   int  StudentId { get ;  set ;} 
  public   string  StudentName { get ;  set ;} 
} 
 
  public   class  Club 
 {
  public   int  ClubId { get  ;  set ;} 
  public   string  ClubName { get ;  set ;} 
} 
 
  public   class  House 
 {
  public   int  HouseId { get ;  set ;} 
  public   string  HouseName { get ;  set ;} 
} 

我需要实现的是计算在我的控制器中使用数据操作方法在Data.cshtml视图中显示多少学生，多少个俱乐部和多少个房子并显示它们



i然后创建了一个模型来获取数据

  public   class 数据
 {
  public   int  StudCount { get ;  set ; } 
 
  public   int  ClubCount {获得;  set ; } 
 
  public   int  HouseCount {获得;  set ; } 
 
 
} 

如何编写linq语句以便能够计算不定义学生，没有俱乐部的，并没有从不同的充表

房子的解决方案

假设你有一个的DbContext（YourDbContext），并使用的DbContext可以编写查询作为下面：

 使用（ var  dbc =  new  YourDbContext（））
 {
  var  noofstudents = dbc.Students。选择（s = >  s.StudentId）.Count（）; 
  var  noofclubs = dbc.Clubs.Select（s => s.ClubId）.Count（）; 
  var  noofhosues = dbc.Houses.Select（s => s.HouseId）.Count（）; 
} 

我认为你的第三个模特课是House而不是学生。

作为ids在每个表中都是主要的（假设），计数将返回你期望的值。

我也使用了复数形式的类作为表名，你替换它们，因为它们在你的名字中命名数据库。



希望这会有所帮助。

i have the following model and table

  public class Student
{
  public int StudentId{get;set;}
  public string StudentName{get;set;}
}

public class Club
{
  public int ClubId{get;set;}
  public string ClubName{get;set;}
}

public class House
{
  public int HouseId{get;set;}
  public string HouseName{get;set;}
}

what i need to acheive is to count how many students, how many clubs and how many house and display them in Data.cshtml view using Data action method in my controller

i then created a model to to get the data

public class Data
    {
        public int StudCount { get; set; }

        public int ClubCount { get; set; }

        public int HouseCount { get; set; }

         
    }

how do i write a linq statement to be able to count no of student, no of club, and no of house from differnt tables

解决方案

Assuming you have a DbContext (YourDbContext) defined and using the DbContext you can write the queries as below:

using(var dbc = new YourDbContext())
{
var noofstudents= dbc.Students.Select(s => s.StudentId).Count();
var noofclubs = dbc.Clubs.Select(s=>s.ClubId).Count();
var noofhosues =dbc.Houses.Select(s=>s.HouseId).Count();
}

I think your third model class is House not student.
As the ids in each table are primary(assuming), the counts will return the values as you expect.
Also I have used the plural forms of the class as table names, you replace them as they are named in your database.

Hope this will help.

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