Hi Paul, 

Once the cell enters edit mode, it has to show the value so that the user can edit. There's really no way around that. 
But if you are only concerned about the display of the cell when it is not in edit mode, you could achieve this very easily by applying a custom Format to the column. Something like this: 

this.ultraGrid1.DisplayLayout.Bands[0].Columns["EntityID"].Format = "g;g; ";

The Format is in 3 sections: positive, negative, and zero. So I used the General format for the first two and a single space character for the zero section. 

Hi Andrew

You will just need a blank form with an ultragrid dropped on it then this is the form code, I want the EnttiyID in row 6 to show nothing like in row 7. I cannot update the database value to null so need to ensure any zeroes are represented as nothing, I would prefer no to have a blank option in the drop down as that will look poor.

Thanks

Paul

public partial class Form1 : Form
    {
        DataTable gridTable;
        DataTable comboTable = new DataTable();
        public Form1()
        {
            InitializeComponent();
            CreateTableAndBindToGrid();
            SetEntityIDToUltraCombo();
        }

        private void CreateTableAndBindToGrid()
        {
            gridTable = new DataTable();
            gridTable.Columns.Add("ID", typeof(int));
            gridTable.Columns.Add("EntityID", typeof(int));
            gridTable.Columns.Add("Description", typeof(String));
            this.gridTable.Rows.Add(new object[] {1, 1, "Paul should be in dropdown" } );
            this.gridTable.Rows.Add(new object[] {2, 2, "John should be in dropdown" });
            this.gridTable.Rows.Add(new object[] {3, 3, "Heidi should be in dropdown" });
            this.gridTable.Rows.Add(new object[] {4, 4, "Fred  should be in dropdown" });
            this.gridTable.Rows.Add(new object[] {5, 3, "Heidi should be in dropdown" });
            this.gridTable.Rows.Add(new object[] {6, 0, "Drop down should be blank but is showing 0" });
            this.gridTable.Rows.Add(new object[] {7, null, "Drop down is blank which is good" });
            this.ultraGrid1.SetDataBinding(this.gridTable, "", true);
        }

        private void SetEntityIDToUltraCombo()
        {
            this.ultraGrid1.DisplayLayout.Bands[0].Columns["EntityID"].EditorComponent = new EntityDropDown(this.BindingContext);
            this.ultraGrid1.DisplayLayout.Bands[0].Columns["EntityID"].Style = Infragistics.Win.UltraWinGrid.ColumnStyle.DropDownValidate;
        }

    }

    public class EntityDropDown : UltraComboEditor
    {
        private DataTable entitiesTable;

        public EntityDropDown(BindingContext bindingContext)
        {
            CreateEntitiesTable();
            this.BindingContext = bindingContext;
            this.DataSource = entitiesTable;
            this.ValueMember = "ID";
            this.AlwaysInEditMode = true;
            this.DisplayMember = "EntityName";
            this.DropDownStyle = Infragistics.Win.DropDownStyle.DropDown;
            this.LimitToList = true;
        }

        private void CreateEntitiesTable()
        {
            this.entitiesTable = new DataTable();
            entitiesTable.Columns.Add("ID", typeof(int));
            entitiesTable.Columns.Add("EntityName", typeof(String));
            entitiesTable.Rows.Add(new object[] { 1, "Paul" });
            entitiesTable.Rows.Add(new object[] { 2, "John" });
            entitiesTable.Rows.Add(new object[] { 3, "Heidi" });
            entitiesTable.Rows.Add(new object[] { 4, "Fred" });
        }
    }