GroupFieldCollection Class

using System;
using System.Windows.Forms;
using DevExpress.XtraReports.UI;
using DevExpress.DataAccess.ConnectionParameters;
using DevExpress.DataAccess.Sql;
using DevExpress.XtraReports.Configuration;
// ...

public XtraReport CreateDataGroupingReport() {
    // Create a report.
    XtraReport report = new XtraReport();

    // Create a data source with the required connection parameters.  
    Access97ConnectionParameters connectionParameters =
        new Access97ConnectionParameters("../../nwind.mdb", "", "");
    SqlDataSource ds = new SqlDataSource(connectionParameters);   
    CustomSqlQuery query = new CustomSqlQuery();
    query.Name = "customQuery";
    query.Sql = "SELECT * FROM CategoryProducts";
    ds.Queries.Add(query);
    ds.RebuildResultSchema();

    // Assign the data source to the report.
    report.DataSource = ds;
    report.DataMember = "customQuery";

    // Create a detail band and add it to the report.
    DetailBand detail = new DetailBand { HeightF = 40 };
    report.Bands.Add(detail);

    // Create a group header band and add it to the report.
    GroupHeaderBand ghBand = new GroupHeaderBand { HeightF = 40 };
    report.Bands.Add(ghBand);

    // Create a group field and assign it to the group header band.
    GroupField groupField = new GroupField("CategoryName");
    ghBand.GroupFields.Add(groupField);

    // Create new labels.
    XRLabel labelGroup = new XRLabel { ForeColor = System.Drawing.Color.Blue };
    XRLabel labelDetail = new XRLabel { LocationF = new System.Drawing.PointF(30, 0) };

    // Specify labels' bindings depending on the report's data binding mode.
    if (Settings.Default.UserDesignerOptions.DataBindingMode == DataBindingMode.Bindings) {
        labelGroup.DataBindings.Add("Text", null, "customQuery.CategoryName");
        labelDetail.DataBindings.Add("Text", null, "customQuery.ProductName");
    } else {
        labelGroup.ExpressionBindings.Add(new ExpressionBinding("BeforePrint", "Text", "[CategoryName]"));
        labelDetail.ExpressionBindings.Add(new ExpressionBinding("BeforePrint", "Text", "[ProductName]"));
    }
    // Add these labels to the report's bands.    
    ghBand.Controls.Add(labelGroup);          
    detail.Controls.Add(labelDetail);

    return report;
}

Imports System
Imports System.Windows.Forms
Imports DevExpress.XtraReports.UI
Imports DevExpress.DataAccess.ConnectionParameters
Imports DevExpress.DataAccess.Sql
Imports DevExpress.XtraReports.Configuration
' ...

Public Function CreateDataGroupingReport() As XtraReport
    ' Create a report.
    Dim report As XtraReport = New XtraReport()

    ' Create a data source with the required connection parameters.
    Dim connectionParameters As Access97ConnectionParameters = New Access97ConnectionParameters("../../nwind.mdb", "",
    Dim ds As SqlDataSource = New SqlDataSource(connectionParameters)
    Dim query As CustomSqlQuery = New CustomSqlQuery()
    query.Name = "customQuery"
    query.Sql = "SELECT * FROM CategoryProducts"
    ds.Queries.Add(query)
    ds.RebuildResultSchema()

    ' Assign the data source to the report.
    report.DataSource = ds
    report.DataMember = "customQuery"

    ' Create a detail band and add it to the report.
    Dim detail As DetailBand = New DetailBand With {.HeightF = 40}
    report.Bands.Add(detail)

    ' Create a group header band and add it to the report.
    Dim ghBand As GroupHeaderBand = New GroupHeaderBand With {.HeightF = 40}
    report.Bands.Add(ghBand)

    ' Create a group field and assign it to the group header band.
    Dim groupField As GroupField = New GroupField("CategoryName")
    ghBand.GroupFields.Add(groupField)

    ' Create new labels.
    Dim labelGroup As XRLabel = New XRLabel With {.ForeColor = System.Drawing.Color.Blue }
    Dim labelDetail As XRLabel = New XRLabel With {.LocationF = New System.Drawing.PointF(30, 0)}

    ' Specify label bindings depending on the report's data binding mode.
    If Settings.[Default].UserDesignerOptions.DataBindingMode = DataBindingMode.Bindings Then
        labelGroup.DataBindings.Add("Text", Nothing, "customQuery.CategoryName")
        labelDetail.DataBindings.Add("Text", Nothing, "customQuery.ProductName")
    Else
        labelGroup.ExpressionBindings.Add(New ExpressionBinding("BeforePrint", "Text", "[CategoryName]"))
        labelDetail.ExpressionBindings.Add(New ExpressionBinding("BeforePrint", "Text", "[ProductName]"))
    End If
    ' Add these labels to the report's bands.
    ghBand.Controls.Add(labelGroup)
    detail.Controls.Add(labelDetail)
    Return report
End Function