C# | SU [ 81 - 89 ] [ FOR JOURNAL ]

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CODE


using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace Definitions
{
    public partial class Form81 : Form
    {
        string connStr = "Data Source=SERVER;Initial Catalog=DB;Integrated Security=True";

        public Form81()
        {
            InitializeComponent();
        }

        private void Form81_Load(object sender, EventArgs e)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                // Create DataAdapters for both Master (Departments) and Detail (Employees) tables
                SqlDataAdapter daMaster = new SqlDataAdapter("SELECT * FROM Departments", conn);
                SqlDataAdapter daDetail = new SqlDataAdapter("SELECT * FROM Employees", conn);

                DataSet ds = new DataSet();

                // Fill the DataSet with both tables
                daMaster.Fill(ds, "Departments");
                daDetail.Fill(ds, "Employees");

                // Create the DataRelation linking the Primary Key to the Foreign Key
                DataColumn masterColumn = ds.Tables["Departments"].Columns["DeptId"];
                DataColumn detailColumn = ds.Tables["Employees"].Columns["DeptId"];
                
                DataRelation relation = new DataRelation("DeptEmpRelation", masterColumn, detailColumn);
                ds.Relations.Add(relation);

                // Bind Master DataGridView to the Departments table
                dgvMaster.DataSource = ds;
                dgvMaster.DataMember = "Departments";

                // Bind Detail DataGridView to the RELATIONSHIP itself to auto-filter child records
                dgvDetail.DataSource = ds;
                dgvDetail.DataMember = "Departments.DeptEmpRelation";
            }
        }
    }
}

OUTPUT

Master-Detail View

Master: Departments

DeptId	DeptName
10	IT
20	HR

Detail: Employees in IT (Dept 10)

EmpId	EmpName	DeptId
101	Alex	10
103	Sara	10

CODE


namespace Definitions
{
    public partial class Form82 : Form
    {
        public Form82()
        {
            InitializeComponent();
        }

        // CREATE: Add item to ListBox
        private void btnAdd_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(txtData.Text))
            {
                listBox1.Items.Add(txtData.Text);
                txtData.Clear();
                txtData.Focus();
            }
        }

        // READ: Populate textbox when an item is selected from ListBox
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex != -1)
            {
                txtData.Text = listBox1.SelectedItem.ToString();
            }
        }

        // UPDATE: Replace the currently selected item
        private void btnUpdate_Click(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex != -1 && !string.IsNullOrWhiteSpace(txtData.Text))
            {
                listBox1.Items[listBox1.SelectedIndex] = txtData.Text;
                txtData.Clear();
            }
            else
            {
                MessageBox.Show("Please select an item to update.");
            }
        }

        // DELETE: Remove the selected item
        private void btnDelete_Click(object sender, EventArgs e)
        {
            if (listBox1.SelectedIndex != -1)
            {
                listBox1.Items.RemoveAt(listBox1.SelectedIndex);
                txtData.Clear();
            }
            else
            {
                MessageBox.Show("Please select an item to delete.");
            }
        }
    }
}

OUTPUT

ListBox CRUD

Data:

Updated Item Text|

Item One

Updated Item Text

Item Three

CODE


// --- CODE FOR FORM 1 (Sender) ---
namespace Definitions
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnSendData_Click(object sender, EventArgs e)
        {
            // Read data from textbox on Form1
            string dataToPass = textBox1.Text;
            
            // Create instance of Form2 and pass data via its constructor
            Form2 form2 = new Form2(dataToPass);
            form2.Show();
        }
    }
}

// --- CODE FOR FORM 2 (Receiver) ---
namespace Definitions
{
    public partial class Form2 : Form
    {
        // Constructor updated to receive a string parameter
        public Form2(string receivedData)
        {
            InitializeComponent();
            
            // Assign the received data to a Label on Form2
            lblReceivedData.Text = "Received: " + receivedData;
        }
    }
}

OUTPUT

Form 1 (Sender)

Hello from Form 1!

→

Form 2 (Receiver)

Received: Hello from Form 1!

CODE


using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace Definitions
{
    // A reusable custom control consisting of a Label and a Button
    public partial class MyCustomControl : UserControl
    {
        // 1. Custom Event definition
        public event EventHandler CustomButtonClicked;

        public MyCustomControl()
        {
            InitializeComponent();
        }

        // 2. Custom Property definition (Shows up in Visual Studio Properties Window)
        [Category("Custom Properties")]
        [Description("Sets the title text of the control.")]
        public string TitleText
        {
            get { return lblTitle.Text; }
            set { lblTitle.Text = value; }
        }

        // Internal button click triggers the public event
        private void btnAction_Click(object sender, EventArgs e)
        {
            // Trigger the event if anyone is subscribed to it
            CustomButtonClicked?.Invoke(this, EventArgs.Empty);
        }
    }
}

OUTPUT

UserControl Designer View

[TitleText Property]

CODE


namespace Definitions
{
    public partial class Form85 : Form
    {
        public Form85()
        {
            InitializeComponent();
        }

        private void Form85_Load(object sender, EventArgs e)
        {
            // 1. Instantiate the custom UserControl programmatically
            MyCustomControl customUC = new MyCustomControl();

            // 2. Set its custom property
            customUC.TitleText = "Dynamic Dashboard Widget";
            
            // 3. Set location on the form
            customUC.Location = new System.Drawing.Point(20, 20);

            // 4. Subscribe to its custom event
            customUC.CustomButtonClicked += CustomUC_CustomButtonClicked;

            // 5. Add it to the Form's Controls collection so it becomes visible
            this.Controls.Add(customUC);
        }

        // Event handler that runs when the UserControl's button is clicked
        private void CustomUC_CustomButtonClicked(object sender, EventArgs e)
        {
            MessageBox.Show("The custom event was caught by the main form!");
        }
    }
}

OUTPUT

Main Window

Dynamic Dashboard Widget

CODE


namespace Definitions
{
    public partial class MDIParent86 : Form
    {
        public MDIParent86()
        {
            InitializeComponent();
            this.IsMdiContainer = true;
        }

        // Triggers when File -> Open File is clicked from the MenuStrip
        private void openFileToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog openDialog = new OpenFileDialog();
            openDialog.Filter = "Text Files|*.txt|All Files|*.*";
            openDialog.Title = "Open a File";

            if (openDialog.ShowDialog() == DialogResult.OK)
            {
                // Create a new child form to display the selection
                Form childForm = new Form();
                childForm.MdiParent = this;
                childForm.Text = "File: " + openDialog.SafeFileName;
                
                Label lbl = new Label() { Text = "Opened: " + openDialog.FileName, AutoSize = true, Top = 20, Left = 20 };
                childForm.Controls.Add(lbl);
                
                childForm.Show();
            }
        }

        // Triggers when File -> Select Color is clicked
        private void selectColorToolStripMenuItem_Click(object sender, EventArgs e)
        {
            ColorDialog colorDialog = new ColorDialog();
            if (colorDialog.ShowDialog() == DialogResult.OK)
            {
                // Changes the MDI background color
                foreach (Control c in this.Controls)
                {
                    if (c is MdiClient)
                    {
                        c.BackColor = colorDialog.Color;
                    }
                }
            }
        }
    }
}

OUTPUT

MDI Application with Dialogs

File

Open File...

Select Color...

Exit

Open a File

📁 Documents
📄 data.txt
📄 notes.txt

File name:

data.txt

CODE


using System;
using System.Windows.Forms;
// Requires CrystalDecisions references
using CrystalDecisions.CrystalReports.Engine; 

namespace Definitions
{
    public partial class Form87 : Form
    {
        public Form87()
        {
            InitializeComponent();
        }

        private void Form87_Load(object sender, EventArgs e)
        {
            try
            {
                // Instantiate the ReportDocument
                ReportDocument cryRpt = new ReportDocument();
                
                // Load the physical .rpt file created in the Crystal Reports designer
                // Assume EmployeeReport.rpt is in the project output directory
                string reportPath = Application.StartupPath + "\\EmployeeReport.rpt";
                cryRpt.Load(reportPath);
                
                // (Optional) If report requires database login credentials:
                // cryRpt.SetDatabaseLogon("username", "password", "server", "database");

                // Assign the report to the viewer control placed on the form
                crystalReportViewer1.ReportSource = cryRpt;
                crystalReportViewer1.Refresh();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error loading report: " + ex.Message);
            }
        }
    }
}

OUTPUT

Report Viewer Form

🖨️ 📤

⏮️ ◀️ 1/1 ▶️ ⏭️

🔍 100% ▼

Employee Data Report

Emp ID	Full Name	Department
101	Alex Johnson	IT
102	Sara Smith	HR
103	David Lee	Finance

Generated on: 16-Mar-2026

CODE


namespace Definitions
{
    public partial class Form88 : Form
    {
        public Form88()
        {
            InitializeComponent();
        }

        private void btnChangeBg_Click(object sender, EventArgs e)
        {
            // Instantiate the built-in ColorDialog
            ColorDialog colorDialog = new ColorDialog();
            
            // Allow user to define custom colors in the dialog
            colorDialog.AllowFullOpen = true; 
            
            // Show the dialog and check if the user clicked "OK"
            if (colorDialog.ShowDialog() == DialogResult.OK)
            {
                // Apply the selected color to the current form's background
                this.BackColor = colorDialog.Color;
            }
        }
    }
}

OUTPUT

Theme Changer

CODE


using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace Definitions
{
    public partial class Form89 : Form
    {
        string connStr = "Data Source=SERVER;Initial Catalog=DB;Integrated Security=True";

        public Form89()
        {
            InitializeComponent();
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            using (SqlConnection conn = new SqlConnection(connStr))
            {
                // SQL query targeting the specific fields and the condition (salary < 3000)
                string query = "SELECT empno, ename, salary FROM Emp WHERE salary < 3000";
                
                using (SqlCommand cmd = new SqlCommand(query, conn))
                {
                    try
                    {
                        conn.Open();
                        SqlDataReader reader = cmd.ExecuteReader();
                        
                        DataTable dt = new DataTable();
                        dt.Load(reader);
                        
                        // Bind results to grid
                        dataGridView1.DataSource = dt;
                        
                        if(dt.Rows.Count == 0)
                        {
                            MessageBox.Show("No employees found with salary less than 3000.");
                        }
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show("Database Error: " + ex.Message);
                    }
                }
            }
        }
    }
}

OUTPUT

Employee Search

Filter: Salary < 3000

empno	ename	salary
E004	Raj Patel	2500.00
E007	Priya Sharma	2850.00
E012	Amit Kumar	2900.00

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Monday, 16 March 2026