防止C1TrueDBGrid中的重复条目

我正在使用我的C#Windows应用程序，这是我第一次使用tdbgrid（component1）。我想防止用户在用数据库验证后输入重复的值。

以下是我在（BeforeColUpdate）事件中使用的代码：

bool ExitValue = false;
private void C1TrueDBGrid_BeforeColUpdate(object sender, C1.Win.C1TrueDBGrid.BeforeColUpdateEventArgs e)
{
    if (e.Column.Name == "Groups Code")
    {
        for (int currentRow = 0; currentRow < this.C1TrueDBGrid.Rows.Count - 1;currentRow++)
        {
            string rowToCompare = this.C1TrueDBGrid.Splits[0].DisplayColumns[C1TrueDBGrid.Col].DataColumn.CellValue(currentRow).ToString();
            for (int otherRow = currentRow+1 ; otherRow < this.C1TrueDBGrid.Rows.Count; otherRow++)
            { 
                bool DuplicatedRow = true;
                string Row = this.C1TrueDBGrid.Splits[0].DisplayColumns[C1TrueDBGrid.Col].DataColumn.CellValue(otherRow).ToString();
                if (Row!=rowToCompare)
                {
                    ExitValue = false;
                    break;
                }
                if (DuplicatedRow)
                {
                    C1TrueDBGrid.Splits[0].DisplayColumns[tgdGroupsUsers.Col].DataColumn.Value = DBNull.Value;
                    MessageBox.Show("Sorry: but this item(s) is already Exists  ", "Error Info", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    ExitValue = true;
                    e.Cancel = true;
                }
            }
        }         
    }
    else
    {
        //Clear Fields
        C1TrueDBGrid.Splits[0].DisplayColumns[C1TrueDBGrid.Col].DataColumn.Value = null;
        e.Cancel = true;
    }
}

如果没有重复，下面是我在（AfterColUpdate）事件中使用的代码：

private void C1TrueDBGrid_AfterColUpdate(object sender, C1.Win.C1TrueDBGrid.ColEventArgs e)
{
    if (!ExitValue)
    {
        int indexRow = this.C1TrueDBGrid.RowBookmark(this.C1TrueDBGrid.Row);
        this.C1TrueDBGrid[indexRow, 0] = CSystemUsers.GroupsCode;
        this.C1TrueDBGrid[indexRow, 0] = CSystemUsers.EngName;
    }
}

private void c1TrueDBGrid1_BeforeColUpdate(object sender, C1.Win.C1TrueDBGrid.BeforeColUpdateEventArgs e)
{
    if (e.ColIndex == 1)
    {
       for (int i = 0; i < c1TrueDBGrid1.RowCount; i++)
       {
        if (c1TrueDBGrid1.Editor.Text == c1TrueDBGrid1[i, e.ColIndex].ToString())
        {
            MessageBox.Show("Sorry: but this item(s) already Exists", "Error Info", MessageBoxButtons.OK, MessageBoxIcon.Information);
            e.Cancel = true;
        }
    }
 }
}