RelateComboBoxHelper
    /// <summary>
    /// Author:武广敬
    /// Blog:tonyepaper.cnblogs.com
    /// 级联菜单帮助类
    /// </summary>
    public class RelateComboBoxHelper
    {
        //未筛选的数据源
        private static BindingSource[] _unFilterBS = new BindingSource[10];
        //筛选后的数据源
        private static BindingSource[] _filterBS = new BindingSource[10];
        //级联主选单
        private static string[] _sourceComboBoxName;
        //级联选单
        private static string[] _filterComboBoxName;
        //Ex:"GoodsNo='{0}'"
        private static string[] _filterExpression;
        /// <summary>
        /// 处理有级联的DataGridViewComboBoxColumn,使从属DataGridViewComboBoxColumn
        /// 可以根据父DataGridViewComboBoxColumn的值改变自身的数据源
        /// </summary>
        /// <param name="dataGridView">需要处理级联的DataGridView</param>
        /// <param name="sourceComboBoxName">级联父DataGridViewComboBoxColumn</param>
        /// <param name="filterComboBoxName">级联子DataGridViewComboBoxColumn</param>
        /// <param name="dataSource">级联子DataGridViewComboBoxColumn的数据源DataTable</param>
        /// <param name="filterExpression">级联子DataGridViewComboBoxColumn根据父DataGridViewComboBoxColumn改变的筛选表达式 Ex:"GoodsNo='{0}'"</param>
        public static void BuildComboBox(DataGridView dataGridView, string sourceComboBoxName, string filterComboBoxName, DataTable dataSource, string filterExpression)
        {
            BuildComboBox(dataGridView, new string[] { sourceComboBoxName }, new string[] { filterComboBoxName }, new DataTable[] { dataSource }, new string[] { filterExpression });
        }
        /// <summary>
        /// 处理有级联的DataGridViewComboBoxColumn,使从属DataGridViewComboBoxColumn(使用下拉选单本身的数据源)
        /// 可以根据父DataGridViewComboBoxColumn的值改变自身的数据源
        /// </summary>
        /// <param name="dataGridView">需要处理级联的DataGridView</param>
        /// <param name="sourceComboBoxName">级联父DataGridViewComboBoxColumn</param>
        /// <param name="filterComboBoxName">级联子DataGridViewComboBoxColumn</param>
        /// <param name="filterExpression">级联子DataGridViewComboBoxColumn根据父DataGridViewComboBoxColumn改变的筛选表达式 Ex:"GoodsNo='{0}'"</param>
        public static void BuildComboBox(DataGridView dataGridView, string sourceComboBoxName, string filterComboBoxName, string filterExpression)
        {
            BuildComboBox(dataGridView, new string[] { sourceComboBoxName }, new string[] { filterComboBoxName }, new DataTable[] { (dataGridView.Columns[filterComboBoxName] as DataGridViewComboBoxColumn).DataSource as DataTable }, new string[] { filterExpression });
        }
        /// <summary>
        /// 处理多个级联的下拉选单
        /// </summary>
        /// <param name="dataGridView">需要处理级联的DataGridView</param>
        /// <param name="sourceComboBoxName">级联父DataGridViewComboBoxColumn</param>
        /// <param name="filterComboBoxName">级联子DataGridViewComboBoxColumn</param>
        /// <param name="dataSource">级联子DataGridViewComboBoxColumn的数据源DataTable</param>
        /// <param name="filterExpression">级联子DataGridViewComboBoxColumn根据父DataGridViewComboBoxColumn改变的筛选表达式 Ex:"GoodsNo='{0}'"</param>
        public static void BuildComboBox(DataGridView dataGridView, string[] sourceComboBoxName, string[] filterComboBoxName, DataTable[] dataSource, string[] filterExpression)
        {
            try
            {
                dataGridView.CellBeginEdit += new DataGridViewCellCancelEventHandler(dataGridView_CellBeginEdit);
                dataGridView.CellEndEdit += new DataGridViewCellEventHandler(dataGridView_CellEndEdit);for (int i = 0; i < sourceComboBoxName.Length; i++)
                {
                    _unFilterBS[i] = new BindingSource();
                    _unFilterBS[i].DataSource = dataSource[i];
                    _filterBS[i] = new BindingSource();
                    _filterBS[i].DataSource = dataSource[i];
                    (dataGridView.Columns[filterComboBoxName[i]] as DataGridViewComboBoxColumn).DataSource = _unFilterBS[i];
                }
                _filterComboBoxName = filterComboBoxName;
                _sourceComboBoxName = sourceComboBoxName;
                _filterExpression = filterExpression;
            }
            catch (Exception ex)
            {
                throw ex;
            }

        }

使用方法

Code
RelateComboBoxHelper.BuildComboBox(DataGridViewName, "级联父列名-如部门", "级联子列名-如部门成员", 所有部门成员数据的DataTable(需要包含[DeptNo列]),"子列名根据父列名筛选内容的筛选字串DeptNo='{0}'");