如何把一个DataTable中的某列通过表关系加到另外一个DataTable中

using System;
using System.Data;

namespace BaseClassLibrary
{
    /**//// <summary>
    /// 基础类
    /// </summary>
    public class DataSetOperate
    {
        /**//// <summary>
        /// 对DataSet进行处理，建立DataTable表间的关系，向DataTable中增加列
        /// </summary>
        public DataSetOperate()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }
        /**//// <summary>
        /// 建立DataTable表间的关系
        /// </summary>
        /// <param name="ds">需要建立关系的DataSet</param>
        /// <param name="primaryTableName">主键表名称</param>
        /// <param name="foreignTableName">外键表名称</param>
        /// <param name="primaryColumnName">主键列名称</param>
        /// <param name="foreignColumnName">外键列名称</param>
        public void newRelation(DataSet ds,string primaryTableName,string foreignTableName,string primaryColumnName,string foreignColumnName)
        {
            DataTable primaryTable = ds.Tables[primaryTableName];
            DataTable foreignTable = ds.Tables[foreignTableName];
            ds.Relations.Add(primaryTableName + foreignTableName,primaryTable.Columns[primaryColumnName],foreignTable.Columns[foreignColumnName]);           
        }
        /**//// <summary>
        /// 先建立DataSet间关系，在向外建表DataTabe中增加列
        /// </summary>
        /// <param name="ds">需要建立关系的DataSet</param>
        /// <param name="primaryTableName">主键表名称</param>
        /// <param name="foreignTableName">外键表名称</param>
        /// <param name="primaryColumnName">主键列名称</param>
        /// <param name="foreignColumnName">外键列名称</param>
        /// <param name="addColumnName">主键表中列名称</param>
        /// <param name="newColumnName">外键表中新增列名称</param>
        public void addColumnWithRelation(DataSet ds,string primaryTableName,string foreignTableName,string primaryColumnName,string foreignColumnName,string addColumnName,string newColumnName)
        {
            DataTable primaryTable = ds.Tables[primaryTableName];
            DataTable foreignTable = ds.Tables[foreignTableName];
            ds.Relations.Add(primaryTableName + foreignTableName,primaryTable.Columns[primaryColumnName],foreignTable.Columns[foreignColumnName]);
            DataColumn newColumn = new DataColumn(newColumnName,ds.Tables[primaryTableName].Columns[addColumnName].DataType);
            ds.Tables[foreignTableName].Columns.Add(newColumn);
            int rowCount = ds.Tables[foreignTableName].Rows.Count;
            for(int i = 0;i < rowCount;i++)
            {
                DataRow parentCustomerDR = foreignTable.Rows[i].GetParentRow(primaryTableName + foreignTableName);
                foreignTable.Rows[i][newColumnName] = parentCustomerDR[addColumnName];
            }
        }