Drop-Down Hierarchical Data Display

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True DBGrid for WinForms allows you to display a master/child relationship between data sources in such a way that the child data records are available from within the master table in a completely new True DBGrid. By simply setting the ChildGrid property to connect two grid controls and a few lines of code, you can create a fully editable drop-down child that appears within the master table with a simple click.

Assuming that your hierarchical dataset is already configured, you can create the master/child relationship by selecting C1TrueDBGrid2 in the ChildGrid property of C1TrueDBGrid1.

Notice that C1TrueDBGrid2 is rendered invisible and there is an expand icon ("+") beside the left most cell in each row. The master table contains a list of composers including vital statistics. Note, that as you scroll right, the expand icon remains in the left most cell at all times.

By left clicking on any of the expand icons, our child table appears in a drop-down window. In this case, the drop-down window lists the written works of the specific composer that you expanded.

The following code demonstrates how simple it is to attach a child grid to its master grid and display hierarchical data in a convenient display. In this example, we have added two TrueDBGrid controls to display hierarchical data.

C#	Copy Code
private void Form1_Load(object sender, EventArgs e) { // Create the DataSet and DataTable string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), @"ComponentOne Samples\Common\C1NWind.mdb") + ";"; OleDbConnection conn = new OleDbConnection(connectionString); OleDbDataAdapter adp_Composer = new OleDbDataAdapter("Select Last, * from Composer", conn); OleDbDataAdapter adp_Opus = new OleDbDataAdapter("Select * from Opus", conn); DataSet data = new DataSet(); DataTable table_Composer = new DataTable(); DataTable table_Opus = new DataTable(); data.Tables.Add(table_Composer); data.Tables.Add(table_Opus); adp_Composer.Fill(table_Composer); adp_Opus.Fill(table_Opus); //Create relation between tables data.Relations.Add("Composer_Sale", data.Tables[table_Composer.TableName].Columns["Last"], data.Tables[table_Opus.TableName].Columns["Last"]); //Bind with the dataset c1TrueDBGrid1.DataSource = data;//MasterGrid c1TrueDBGrid2.DataSource = data;// ChildGrid c1TrueDBGrid1.DataMember = table_Composer.TableName; //Provide master grid data member and data relation name to the child grid data member c1TrueDBGrid2.DataMember = c1TrueDBGrid1.DataMember + ".Composer_Sale"; //Set the Child grid c1TrueDBGrid1.ChildGrid = c1TrueDBGrid2; }

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private void Form1_Load(object sender, EventArgs e)
{            
    // Create the DataSet and DataTable 
    string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" +
        System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments),
        @"ComponentOne Samples\Common\C1NWind.mdb") + ";";
    OleDbConnection conn = new OleDbConnection(connectionString);

    OleDbDataAdapter adp_Composer = new OleDbDataAdapter("Select Last, * from Composer", conn);
    OleDbDataAdapter adp_Opus = new OleDbDataAdapter("Select * from Opus", conn);

    DataSet data = new DataSet();

    DataTable table_Composer = new DataTable();
    DataTable table_Opus = new DataTable();

    data.Tables.Add(table_Composer);
    data.Tables.Add(table_Opus);

    adp_Composer.Fill(table_Composer);
    adp_Opus.Fill(table_Opus);

    //Create relation between tables
    data.Relations.Add("Composer_Sale", data.Tables[table_Composer.TableName].Columns["Last"],
         data.Tables[table_Opus.TableName].Columns["Last"]);

    //Bind with the dataset
    c1TrueDBGrid1.DataSource = data;//MasterGrid
    c1TrueDBGrid2.DataSource = data;// ChildGrid
    c1TrueDBGrid1.DataMember = table_Composer.TableName;
    //Provide master grid data member and data relation name to the child grid data member 
    c1TrueDBGrid2.DataMember = c1TrueDBGrid1.DataMember + ".Composer_Sale";

    //Set the Child grid
    c1TrueDBGrid1.ChildGrid = c1TrueDBGrid2;
}