linq查询结果中缺少属性
本文关键字:属性 查询 结果 linq | 更新日期: 2023-09-27 18:22:48
请在下面找到linq查询
var result = (
from sd in students
select sd.Student_ID
).Except(
from m in query1
select m.Student_ID
).ToList();
从这个查询中,我得到了确切的结果。现在我想填充学生的其他数据,所以我所做的是编写其他linq查询。下面是,但我没有得到r.Student_ID属性来与学生表进行比较Intellisense未提供r.Student_ID。请帮助!
var finalResult = (
from sd in dbcDefaulter.Student_Details
from r in result
where r == sd.Student_ID
orderby sd.Student_ID
select new { sd.Student_ID, sd.Name, sd.Class, sd.Section, sd.F_Name, sd.F_Mobile }
).Distinct().ToList();
请在此处找到完整的designer.cs
Student_Details类的一部分如下所示:
[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Student_Detail")]
public partial class Student_Detail
{
private int _Student_ID;
private string _Class;
private string _Section;
private string _Session;
private string _Name;
private System.Nullable<System.DateTime> _B_Date;
private string _E_Mail;
private string _Gender;
private string _F_Name;
//From Jesse: Please insert the property definition for Student and/or Students, and/or Student_ID here if available.
}
get set
属性的一部分如下所示:
public DefaulterDataContext(System.Data.IDbConnection connection, System.Data.Linq.Mapping.MappingSource mappingSource) :
base(connection, mappingSource)
{
OnCreated();
}
public System.Data.Linq.Table<Student_Detail> Student_Details
{
get
{
return this.GetTable<Student_Detail>();
}
}
public System.Data.Linq.Table<Fees_Due> Fees_Dues
{
get
{
return this.GetTable<Fees_Due>();
}
}
请找到我们在第一个查询result
中使用的query1
和students
的定义。所以query1
是-
var query1 = (from fd in dbcDefaulter.Fees_Dues
join sd in dbcDefaulter.Student_Details on Convert.ToInt32(fd.Student_ID) equals sd.Student_ID
where fd.Session == GlobalVariables.Session && (fd.Month.Contains(cmbMonth.SelectedItem.ToString()))
orderby fd.Student_ID
select new { sd.Student_ID, fd.Month, fd.Session }).Distinct();
CCD_ 7为-
var students = (from sd in dbcDefaulter.Student_Details
select sd).ToList();
您可以考虑使用List<T>.Contains(aValue)
而不是加入;这也解决了您在提供的另一个解决方案中使用Instance argument: cannot convert from 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Linq.IQueryable<int>'
时遇到的问题:
var result = (
from sd in students
select sd.Student_ID
).Except(
from m in query1
select m.Student_ID
).ToList();
var finalResult = (
from sd in dbcDefaulter.Student_Details
where result.Contains(sd.Student_ID)
orderby sd.Student_ID
select
new { sd.Student_ID, sd.Name, sd.Class, sd.Section, sd.F_Name, sd.F_Mobile}
).Distinct().ToList();
根据您提供的信息,这就是您应该如何更新代码:
// Updated first query to return the Student_ID in an anonymous class.
var result = (from sd in students select new {Student_ID = sd.Student_ID})
.Except(from m in query1 select m.Student_ID).ToList();
// Updated second query to use Join statement
var finalResult = (
from sd in dbcDefaulter.Student_Details
join r in result on sd.Student_ID equals r.Student_ID
orderby sd.Student_ID
select new {sd.Student_ID, sd.Name, sd.Class, sd.Section, sd.F_Name, sd.F_Mobilez
).Distinct().ToList();