/// <summary>
/// 两表LeftJoin关联
/// </summary>
/// <param name="tableName">关联表名</param>
/// <param name="joinOnName">关联的字段名，设置Null则自动取表主键为关联名</param>
/// <param name="appendColumns">追加显示的列，没有指定则追加关联表的所有列</param>
/// <returns></returns>
public MDataTable Join(object tableName, string joinOnName, params string[] appendColumns)
{
return(MDataTableJoin.Join(this, Convert.ToString(tableName), joinOnName, appendColumns));
}
/// <summary>
/// 两表LeftJoin关联
/// </summary>
/// <param name="dt">关联表</param>
/// <param name="appendColumns">追加显示的列，没有指定则追加关联表的所有列</param>
/// <returns></returns>
public MDataTable Join(MDataTable dt, params string[] appendColumns)
{
return(MDataTableJoin.Join(this, dt, appendColumns));
}