How to group columns in gridview header row in ASP.NET (programmer friendly way)

Step - 1 : Create New Project.

Go to File > New > Project > Select asp.net web forms application > Entry Application Name > Click OK.

Step-2: Add a Database.

Go to Solution Explorer > Right Click on App_Data folder > Add > New item > Select SQL Server Database Under Data > Enter Database name > Add.

Step-3: Create table for fetch data.

Open Database > Right Click on Table > Add New Table > Add Columns > Save > Enter table name > Ok.

In this example, I have used one tables as below

Step-4: Add Entity Data Model.

Go to Solution Explorer > Right Click on Project name form Solution Explorer > Add > New item > Select ADO.net Entity Data Model under data > Enter model name > Add.
A popup window will come (Entity Data Model Wizard) > Select Generate from database > Next >


Chose your data connection > select your database > next > Select tables > enter Model Namespace > Finish.

Step-5: Add a Webpage and Design for Show Data in Gridview With Group Column

Go to Solution Explorer > Right Click on Project name form Solution Explorer > Add > New item > Select web form/ web form using master page under Web > Enter page name > Add.

HTML Code 

     <h3> Group columns in gridview header row in ASP.NET (programmer friendly way)</h3><br />
    <asp:GridView ID="GridView1" runat="server" CellPadding="5" AutoGenerateColumns="false" HeaderStyle-BackColor="#f3f3f3" BackColor="White">
        <Columns>
            <asp:BoundField HeaderText="Column 1" DataField="Column1" ControlStyle-CssClass="Group 1" />
            <asp:BoundField HeaderText="Column 2" DataField="Column2" ControlStyle-CssClass="Group 1" />
            <asp:BoundField HeaderText="Column 3" DataField="Column3" ControlStyle-CssClass="Group 1" />
            <asp:BoundField HeaderText="Column 4" DataField="Column4" ControlStyle-CssClass="Group 2" />
            <asp:BoundField HeaderText="Column 5" DataField="Column5" ControlStyle-CssClass="Group 2" />
            <asp:BoundField HeaderText="Column 6" DataField="Column6"  />
            <asp:BoundField HeaderText="Column 7" DataField="Column7"  />
            <asp:BoundField HeaderText="Column 8" DataField="Column8"  />            
        </Columns>
    </asp:GridView>
        

Step-6: Write following code in Page_Load event for Show data in Gridview With grouping column.

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                PopulateData();
            }
        }
        

and here is the function

private void PopulateData()
            {
                using (MyDatabaseEntities dc = new MyDatabaseEntities())
                {
                    GridView1.DataSource = dc.SampleDatas.ToList();
                    GridView1.DataBind();
                }
                // Add Group Header
                SetGroupHeader();
            }
        

Additional this 2 function are required to Add group Columns header....

            private void SetGroupHeader()
            {
                int count = 1;
                string groupName = "";
                List<TableCell> headerCells = new List<TableCell>();
                if (GridView1.Rows.Count > 0)
                {
                    foreach (DataControlField col in GridView1.Columns)
                    {
                        if (col.ControlStyle.CssClass != groupName)
                        {
                            if (groupName != "")
                            {
                                headerCells.Add(GetGroupHeader(groupName, count));
                                count = 1;
                            }
 
                        }
                        else
                        {
                            count++;
                        }
                        groupName = col.ControlStyle.CssClass;
                    }
                    if (count > 1)
                    {
                        headerCells.Add(GetGroupHeader(groupName,count));
                    }
                }
                if (headerCells.Count > 0)
                {
                    GridViewRow gvrow = new GridViewRow(0, 0, DataControlRowType.Header, DataControlRowState.Normal);
                    foreach (TableCell tc in headerCells)
                    {
                        gvrow.Cells.Add(tc);
                    }
                    GridView1.Controls[0].Controls.AddAt(0, gvrow);
                }
            }
        

            private TableCell GetGroupHeader(string headerText, int colSpan)
            {
                TableCell headerCell = new TableCell();
                headerCell.Text = headerText;
                headerCell.ColumnSpan = colSpan;
                return headerCell;
            }
        

Step-7: Run Application.