Use from where select to choose the Employees in the IT department from a tree : Query « LINQ « C# / CSharp Tutorial

Home
C# / CSharp Tutorial
1.Language Basics
2.Data Type
3.Operator
4.Statement
5.String
6.struct
7.Class
8.Operator Overload
9.delegate
10.Attribute
11.Data Structure
12.Assembly
13.Date Time
14.Development
15.File Directory Stream
16.Preprocessing Directives
17.Regular Expression
18.Generic
19.Reflection
20.Thread
21.I18N Internationalization
22.LINQ
23.GUI Windows Forms
24.Windows Presentation Foundation
25.Windows Communication Foundation
26.Workflow
27.2D
28.Design Patterns
29.Windows
30.XML
31.XML LINQ
32.ADO.Net
33.Network
34.Directory Services
35.Security
36.unsafe
C# / C Sharp
C# / C Sharp by API
C# / CSharp Open Source
C# / CSharp Tutorial » LINQ » Query 
22.3.7.Use from where select to choose the Employees in the IT department from a tree
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class Tree<TreeNode> : IEnumerable<TreeNode> where TreeNode : IComparable<TreeNode> {
    public Tree(TreeNode nodeValue) {
        this.NodeData = nodeValue;
        this.LeftTree = null;
        this.RightTree = null;
    }

    public void Insert(TreeNode newItem) {
        TreeNode currentNodeValue = this.NodeData;
        if (currentNodeValue.CompareTo(newItem0) {
            if (this.LeftTree == null) {
                this.LeftTree = new Tree<TreeNode>(newItem);
            else {
                this.LeftTree.Insert(newItem);
            }
        else {
            if (this.RightTree == null) {
                this.RightTree = new Tree<TreeNode>(newItem);
            else {
                this.RightTree.Insert(newItem);
            }
        }
    }

    public void WalkTree() {
        if (this.LeftTree != null) {
            this.LeftTree.WalkTree();
        }

        Console.WriteLine(this.NodeData.ToString());

        if (this.RightTree != null) {
            this.RightTree.WalkTree();
        }
    }

    public TreeNode NodeData get; set; }
    public Tree<TreeNode> LeftTree get; set; }
    public Tree<TreeNode> RightTree get; set; }


    IEnumerator<TreeNode> IEnumerable<TreeNode>.GetEnumerator() {
        if (this.LeftTree != null) {
            foreach (TreeNode item in this.LeftTree) {
                yield return item;
            }
        }

        yield return this.NodeData;

        if (this.RightTree != null) {
            foreach (TreeNode item in this.RightTree) {
                yield return item;
            }
        }
    }
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
        throw new NotImplementedException();
    }
}

class Employee : IComparable<Employee> {
    public string FirstName get; set; }
    public string LastName get; set; }
    public string Department get; set; }
    public int Id get; set; }

    public override string ToString() {
        return String.Format("Id: {0}, Name: {1} {2}, Dept: {3}"this.Id, this.FirstName, this.LastName, this.Department);
    }
    int IComparable<Employee>.CompareTo(Employee other) {
        if (other == null)
            return 1;

        if (this.Id > other.Id)
            return 1;

        if (this.Id < other.Id)
            return -1;

        return 0;
    }
}

class Program {
    static void Main() {
        Tree<Employee> empTree = new Tree<Employee>(new Employee Id = 1, FirstName = "Janet", LastName = "Gates", Department = "IT" });
        empTree.Insert(new Employee Id = 2, FirstName = "O", LastName = "G", Department = "Marketing" });
        empTree.Insert(new Employee Id = 4, FirstName = "K", LastName = "H", Department = "IT" });
        empTree.Insert(new Employee Id = 6, FirstName = "L", LastName = "H", Department = "Sales" });
        empTree.Insert(new Employee Id = 3, FirstName = "E", LastName = "L", Department = "Sales" });
        empTree.Insert(new Employee Id = 5, FirstName = "D", LastName = "L", Department = "Marketing" });

        var ITEmployees = from e in empTree
                          where String.Equals(e.Department, "IT")
                          select e;

        foreach (var emp in ITEmployees)
            Console.WriteLine(emp);
    }
}
22.3.Query
22.3.1.Query Expression
22.3.2.Chaining Query Operators/extracts all strings containing the letter 'a', sorts them by length, and then converts the results to uppercase
22.3.3.Use Contains, Length and ToUpper from Linq
22.3.4.Use select to retrieve all nodes in a Binary tree
22.3.5.Get Distinct departments with condition
22.3.6.Use LINQ to get Employees in the IT department from a tree
22.3.7.Use from where select to choose the Employees in the IT department from a tree
22.3.8.All employees in a tree are grouped by department
22.3.9.ArrayList Query
22.3.10.Complex Query Using Method Syntax
22.3.11.group query
22.3.12.query with extension methods
22.3.13.Join Query
22.3.14.Conduct query on the result again
22.3.15.Use a LINQ query to find the public enums
22.3.16.Define the query using IndexArray first.
22.3.17.Define the query using two from keywords.
22.3.18.Using Linq to get all methods
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.