视觉工作室 2008 | 银光 3 | SQL Server 2005 | 域服务类 | 实体数据模型
我有一个数据库表“学生”，其中包含 FirstName、LastName、Semester、ProgramOfStudy、Column 等列......
目标是根据给定Semester和Programofstudy中所有学生的姓氏的第一个字母返回一个总数（按姓氏的第一个字母分组的学生人数） 。
我没有成功编写 LINQ 查询，并认为我会尝试使用 SQL 视图。
- 创建了视图（17,000 行分组到 5000 行）。
- 视图由“LastNameStartsWith”、“Total”、“AcademicPeriod”、“ProgramCode”组成。
- 将视图添加到 .edmx 模型
- 写了以下查询。
作为林克；
public IQueryable GetVw_studentAlphabetSet(int cycleID, string progCode)
{
var query = from s in db.vw_studentAlphabetSet
where ((s.programCode == progCode) && (s.academicPeriod == cycleID))
select s;
return query;
}
当在 MSSMS 中填充参数作为 sql 运行时，视图过滤到 25 行报告出现次数。AZ，没有报告 X，因为没有以 X 开头的姓氏。
如果在返回查询上设置断点；它会正确报告实体计数 24，但每个实体都是相同的。LastNamesStartsWith = 'A' 和总计 = 21。
所以看起来过滤正在工作，但有一个错误。每个实体都应该是唯一的 AZ。
如果我添加到 .Where 像这样
where (s.programCode == progCode) && (s.academicPeriod == cycleID) && (s.LastNameStartsWith == "B");
产生正确的回报。B, 35, 200890, BSED-ELED-ED
当使用 Linq 返回元素时，我得到了一个微不足道的元素来使用。LastNameStartsWith = "A" 和 Total = 21。但 B - Z 又没有返回总数。在域服务类中，它确实报告了元素计数为 24。它们都去了哪里。即使它们都报告 A 和 21，我也应该再获得 23 个元素。
那么在使用视图和 Linq 时，有什么特别的事情应该知道吗？
这里是实体模型的设计器
[assembly: global::System.Data.Objects.DataClasses.EdmSchemaAttribute()]
// Original file name:
// Generation date: 2/21/2010 10:25:00 PM
namespace sproc.Web
{
///
/// There are no comments for GLADYS_2010Entities in the schema.
///
public partial class GLADYS_2010Entities : global::System.Data.Objects.ObjectContext
{
///
/// Initializes a new GLADYS_2010Entities object using the connection string found in the 'GLADYS_2010Entities' section of the application configuration file.
///
public GLADYS_2010Entities() :
base("name=GLADYS_2010Entities", "GLADYS_2010Entities")
{
this.OnContextCreated();
}
///
/// Initialize a new GLADYS_2010Entities object.
///
public GLADYS_2010Entities(string connectionString) :
base(connectionString, "GLADYS_2010Entities")
{
this.OnContextCreated();
}
///
/// Initialize a new GLADYS_2010Entities object.
///
public GLADYS_2010Entities(global::System.Data.EntityClient.EntityConnection connection) :
base(connection, "GLADYS_2010Entities")
{
this.OnContextCreated();
}
partial void OnContextCreated();
///
/// There are no comments for vw_studentAlphabet in the schema.
///
public global::System.Data.Objects.ObjectQuery vw_studentAlphabet
{
get
{
if ((this._vw_studentAlphabet == null))
{
this._vw_studentAlphabet = base.CreateQuery("[vw_studentAlphabet]");
}
return this._vw_studentAlphabet;
}
}
private global::System.Data.Objects.ObjectQuery _vw_studentAlphabet;
///
/// There are no comments for vw_studentAlphabet in the schema.
///
public void AddTovw_studentAlphabet(vw_studentAlphabet vw_studentAlphabet)
{
base.AddObject("vw_studentAlphabet", vw_studentAlphabet);
}
}
///
/// There are no comments for GLADYS_2010Model.vw_studentAlphabet in the schema.
///
///
/// academicPeriod
/// programCode
///
[global::System.Data.Objects.DataClasses.EdmEntityTypeAttribute(NamespaceName="GLADYS_2010Model", Name="vw_studentAlphabet")]
[global::System.Runtime.Serialization.DataContractAttribute(IsReference=true)]
[global::System.Serializable()]
public partial class vw_studentAlphabet : global::System.Data.Objects.DataClasses.EntityObject
{
///
/// Create a new vw_studentAlphabet object.
///
/// Initial value of academicPeriod.
/// Initial value of programCode.
public static vw_studentAlphabet Createvw_studentAlphabet(int academicPeriod, string programCode)
{
vw_studentAlphabet vw_studentAlphabet = new vw_studentAlphabet();
vw_studentAlphabet.academicPeriod = academicPeriod;
vw_studentAlphabet.programCode = programCode;
return vw_studentAlphabet;
}
///
/// There are no comments for Property LastNameStartsWith in the schema.
///
[global::System.Data.Objects.DataClasses.EdmScalarPropertyAttribute()]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public string LastNameStartsWith
{
get
{
return this._LastNameStartsWith;
}
set
{
this.OnLastNameStartsWithChanging(value);
this.ReportPropertyChanging("LastNameStartsWith");
this._LastNameStartsWith = global::System.Data.Objects.DataClasses.StructuralObject.SetValidValue(value, true);
this.ReportPropertyChanged("LastNameStartsWith");
this.OnLastNameStartsWithChanged();
}
}
private string _LastNameStartsWith;
partial void OnLastNameStartsWithChanging(string value);
partial void OnLastNameStartsWithChanged();
///
/// There are no comments for Property Total in the schema.
///
[global::System.Data.Objects.DataClasses.EdmScalarPropertyAttribute()]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public global::System.Nullable Total
{
get
{
return this._Total;
}
set
{
this.OnTotalChanging(value);
this.ReportPropertyChanging("Total");
this._Total = global::System.Data.Objects.DataClasses.StructuralObject.SetValidValue(value);
this.ReportPropertyChanged("Total");
this.OnTotalChanged();
}
}
private global::System.Nullable _Total;
partial void OnTotalChanging(global::System.Nullable value);
partial void OnTotalChanged();
///
/// There are no comments for Property academicPeriod in the schema.
///
[global::System.Data.Objects.DataClasses.EdmScalarPropertyAttribute(EntityKeyProperty=true, IsNullable=false)]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public int academicPeriod
{
get
{
return this._academicPeriod;
}
set
{
this.OnacademicPeriodChanging(value);
this.ReportPropertyChanging("academicPeriod");
this._academicPeriod = global::System.Data.Objects.DataClasses.StructuralObject.SetValidValue(value);
this.ReportPropertyChanged("academicPeriod");
this.OnacademicPeriodChanged();
}
}
private int _academicPeriod;
partial void OnacademicPeriodChanging(int value);
partial void OnacademicPeriodChanged();
///
/// There are no comments for Property programCode in the schema.
///
[global::System.Data.Objects.DataClasses.EdmScalarPropertyAttribute(EntityKeyProperty=true, IsNullable=false)]
[global::System.Runtime.Serialization.DataMemberAttribute()]
public string programCode
{
get
{
return this._programCode;
}
set
{
this.OnprogramCodeChanging(value);
this.ReportPropertyChanging("programCode");
this._programCode = global::System.Data.Objects.DataClasses.StructuralObject.SetValidValue(value, false);
this.ReportPropertyChanged("programCode");
this.OnprogramCodeChanged();
}
}
private string _programCode;
partial void OnprogramCodeChanging(string value);
partial void OnprogramCodeChanged();
}
}
这是调用域服务和实体模型的客户端代码。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Ria.Data;
using GLADYS.Web.GladysDataLayers;
using GLADYS.Web.GladysServices;
namespace GLADYS
{
public partial class uc_AlphabetFilter : UserControl
{
//data context for getting the data through the ria service.
private dscStudents ctx = new dscStudents();
public uc_AlphabetFilter()
{
InitializeComponent();
//Loaded += new RoutedEventHandler(uc_AlphabetFilter_Loaded);
ctx.Load(ctx.GetVw_studentAlphabetSetQuery(200980, "BSED-ELED-ED")).Completed += new EventHandler(uc_AlphabetFilter_Completed);
}
void uc_AlphabetFilter_Completed(object sender, EventArgs e)
{
foreach (var q in ctx.vw_studentAlphabets)
{
uc_AlphaButton btn = new uc_AlphaButton();
btn.pAlphaLetter = q.LastNameStartsWith;
btn.PNumber = q.Total.Value;
myWrapPanel.Children.Add(btn);
}
}
这里也提出了同样的问题，但采用了不同的方法。