Merge Windows Form DataGridView rows using C# and VB.Net

Hi smile,

You need to use the CellPainting and the CellFormatting event and set the BorderStyle and the cell value.

Plese refer below sample.

Code

C#

public Form1()
{
    InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[4]{new DataColumn ("Id"),
                                            new DataColumn ("Test"),
                                            new DataColumn ("Subject"),
                                            new DataColumn ("Question") });
    dt.Rows.Add(1, "Test1", "English", "Words William is a poet");
    dt.Rows.Add(2, "Test1", "English", "Dafodial written by?");
    dt.Rows.Add(3, "Test2", "Math", "a+b = c");
    dt.Rows.Add(4, "Test2", "Math", "b+c= a");
    dt.Rows.Add(5, "Test2", "Science", "Science is practical activity");
    dt.Rows.Add(6, "Test3", "Computer Science", "Keyboard is an input device");
    dt.Rows.Add(7, "Test3", "Computer Science", "Printer is an output device");
    dgvStudents.DataSource = dt;
    dgvStudents.AllowUserToAddRows = false;
}

private void OnCellPainting(object sender, DataGridViewCellPaintingEventArgs e)
{
    e.AdvancedBorderStyle.Bottom = DataGridViewAdvancedCellBorderStyle.None;
    if (e.RowIndex < 1 || e.ColumnIndex < 0)
    {
        return;
    }
    if (this.IsCellValueSame(e.ColumnIndex, e.RowIndex))
    {
        e.AdvancedBorderStyle.Top = DataGridViewAdvancedCellBorderStyle.None;
    }
    else
    {
        e.AdvancedBorderStyle.Top = dgvStudents.AdvancedCellBorderStyle.Top;
    }
}

private void OnCellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    if (e.RowIndex > 0)
    {
        if (this.IsCellValueSame(e.ColumnIndex, e.RowIndex))
        {
            e.Value = "";
        }
    }
}

protected bool IsCellValueSame(int column, int row)
{
    DataGridViewCell cell1 = dgvStudents[column, row];
    DataGridViewCell cell2 = dgvStudents[column, row - 1];
    if (cell1.Value == null || cell2.Value == null)
    {
        return false;
    }
    return cell1.Value.ToString() == cell2.Value.ToString();
}

VB.Net

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Dim dt As DataTable = New DataTable()
    dt.Columns.AddRange(New DataColumn(3) {New DataColumn("Id"),
                                           New DataColumn("Test"),
                                           New DataColumn("Subject"),
                                           New DataColumn("Question")})
    dt.Rows.Add(1, "Test1", "English", "Words William is a poet")
    dt.Rows.Add(2, "Test1", "English", "Dafodial written by?")
    dt.Rows.Add(3, "Test2", "Math", "a+b = c")
    dt.Rows.Add(4, "Test2", "Math", "b+c= a")
    dt.Rows.Add(5, "Test2", "Science", "Science is practical activity")
    dt.Rows.Add(6, "Test3", "Computer Science", "Keyboard is an input device")
    dt.Rows.Add(7, "Test3", "Computer Science", "Printer is an output device")
    dgvStudents.DataSource = dt
    dgvStudents.AllowUserToAddRows = False
End Sub

Private Sub OnCellPainting(ByVal sender As Object, ByVal e As DataGridViewCellPaintingEventArgs) Handles dgvStudents.CellPainting
    e.AdvancedBorderStyle.Bottom = DataGridViewAdvancedCellBorderStyle.None
    If e.RowIndex < 1 OrElse e.ColumnIndex < 0 Then
        Return
    End If
    If Me.IsCellValueSame(e.ColumnIndex, e.RowIndex) Then
        e.AdvancedBorderStyle.Top = DataGridViewAdvancedCellBorderStyle.None
    Else
        e.AdvancedBorderStyle.Top = dgvStudents.AdvancedCellBorderStyle.Top
    End If
End Sub

Private Sub OnCellFormatting(ByVal sender As Object, ByVal e As DataGridViewCellFormattingEventArgs) Handles dgvStudents.CellFormatting
    If e.RowIndex > 0 Then
        If Me.IsCellValueSame(e.ColumnIndex, e.RowIndex) Then
            e.Value = ""
        End If
    End If
End Sub

Protected Function IsCellValueSame(ByVal column As Integer, ByVal row As Integer) As Boolean
    Dim cell1 As DataGridViewCell = dgvStudents(column, row)
    Dim cell2 As DataGridViewCell = dgvStudents(column, row - 1)
    If cell1.Value Is Nothing OrElse cell2.Value Is Nothing Then
        Return False
    End If
    Return cell1.Value.ToString() = cell2.Value.ToString()
End Function

Screenshot