Get Distinct departments with condition : Query « LINQ « C# / C Sharp

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C# / C Sharp » LINQ » QueryScreenshots 
Get Distinct departments with condition
 

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 depts = empTree.Select(d => d.Department).Distinct();

        foreach (var dept in depts)
            Console.WriteLine("Department: {0}", dept);

    }
}

 
Related examples in the same category
1.Chaining Query Operators/extracts all strings containing the letter "a", sorts them by length, and then converts the results to uppercase
2.Use Contains, Length and ToUpper from Linq
3.Use select to retrieve all nodes in a Binary tree
4.Use LINQ to get Employees in the IT department from a tree
5.Use from where select to choose the Employees in the IT department from a tree
6.All employees in a tree are grouped by department
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