public static class DataTableHelper
{
    public enum JoinType
    {
        /// <summary>
        /// Same as regular join. Inner join produces only the set of records that match in both Table A and Table B.
        /// </summary>
        Inner = 0,/// <summary>
        /// Same as Left Outer join. Left outer join produces a complete set of records from Table A,with the matching records (where available) in Table B. If there is no match,the right side will contain null.
        /// </summary>
        Left = 1
    }
 
    /// <summary>
    /// Joins the passed in DataTables on the colToJoinOn.
    /// <para>Returns an appropriate DataTable with zero rows if the colToJoinOn does not exist in both tables.</para>
    /// </summary>
    /// <param name="dtblLeft"></param>
    /// <param name="dtblRight"></param>
    /// <param name="colToJoinOn"></param>
    /// <param name="joinType"></param>
    /// <returns></returns>
    /// <remarks>
    /// <para>https://stackoverflow.com/questions/2379747/create-combined-datatable-from-two-datatables-joined-with-linq-c-sharp?rq=1</para>
    /// <para>http://msdn.microsoft.com/en-us/library/vstudio/bb397895.aspx</para>
    /// <para>http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html</para>
    /// <para>https://stackoverflow.com/questions/406294/left-join-and-left-outer-join-in-sql-server</para>
    /// </remarks>
    public static DataTable JoinTwoDataTablesOnOneColumn(DataTable dtblLeft,DataTable dtblRight,string colToJoinOn,JoinType joinType)
    {
        //Change column name to a temp name so the LINQ for getting row data will work properly.
        string strTempColName = colToJoinOn + "_2";
        if (dtblRight.Columns.Contains(colToJoinOn))
            dtblRight.Columns[colToJoinOn].ColumnName = strTempColName;
 
        //Get columns from dtblLeft
        DataTable dtblResult = dtblLeft.Clone();
 
        //Get columns from dtblRight
        var dt2Columns = dtblRight.Columns.OfType<DataColumn>().Select(dc => new DataColumn(dc.ColumnName,dc.ColumnMapping));
 
        //Get columns from dtblRight that are not in dtblLeft
        var dt2FinalColumns = from dc in dt2Columns.AsEnumerable()
                              where !dtblResult.Columns.Contains(dc.ColumnName)
                              select dc;
 
        //Add the rest of the columns to dtblResult
        dtblResult.Columns.AddRange(dt2FinalColumns.ToArray());
 
        //No reason to continue if the colToJoinOn does not exist in both DataTables.
        if (!dtblLeft.Columns.Contains(colToJoinOn) || (!dtblRight.Columns.Contains(colToJoinOn) && !dtblRight.Columns.Contains(strTempColName)))
        {
            if (!dtblResult.Columns.Contains(colToJoinOn))
                dtblResult.Columns.Add(colToJoinOn);
            return dtblResult;
        }
 
        switch (joinType)
        {
 
            default:
            case JoinType.Inner:
                #region Inner
                //get row data
                //To use the DataTable.AsEnumerable() extension method you need to add a reference to the System.Data.DataSetExtension assembly in your project. 
                var rowDataLeftInner = from rowLeft in dtblLeft.AsEnumerable()
                                       join rowRight in dtblRight.AsEnumerable() on rowLeft[colToJoinOn] equals rowRight[strTempColName]
                                       select rowLeft.ItemArray.Concat(rowRight.ItemArray).ToArray();
 
 
                //Add row data to dtblResult
                foreach (object[] values in rowDataLeftInner)
                    dtblResult.Rows.Add(values);
 
                #endregion
                break;
            case JoinType.Left:
                #region Left
                var rowDataLeftOuter = from rowLeft in dtblLeft.AsEnumerable()
                                       join rowRight in dtblRight.AsEnumerable() on rowLeft[colToJoinOn] equals rowRight[strTempColName] into gj
                                       from subRight in gj.DefaultIfEmpty()
                                       select rowLeft.ItemArray.Concat((subRight== null) ? (dtblRight.NewRow().ItemArray) :subRight.ItemArray).ToArray();
 
 
                //Add row data to dtblResult
                foreach (object[] values in rowDataLeftOuter)
                    dtblResult.Rows.Add(values);
 
                #endregion
                break;
        }
 
        //Change column name back to original
        dtblRight.Columns[strTempColName].ColumnName = colToJoinOn;
 
        //Remove extra column from result
        dtblResult.Columns.Remove(strTempColName);
 
        return dtblResult;
    }
}

编辑3：

该方法现在可以正常工作,并且当表具有2000行时,该方法仍然很快.任何建议/建议/改进将不胜感激.

编辑4：

我有一些情况导致我意识到,以前的版本是真正做一个内在的联合.该功能已被修改以解决该问题.我使用这个link的信息来弄清楚.