最早写的自定义分页

/// <summary>
        /// 返还分好页的数据源
        /// </summary>
        /// <param name="wherestr">条件</param>
        /// <param name="tablename">表名</param>
        /// <param name="prime_key">主键</param>
        /// <param name="orderzd">排序字段</param>
        /// <param name="currpageindex">当前页</param>
        /// <param name="mydtsouce">数据源</param>
        /// <param name="paddnum">页码</param>
        /// <param name="myorders">排序方式</param>
        /// <returns></returns>
        public DataTable getpsdsouce(string wherestr, string tablename, string prime_key, string orderzd, int currpageindex, DataTable mydtsouce, int paddnum, string myorders)
        {
            DataTable dtsource = new DataTable();
            dtsource = mydtsouce;
            int paddingnum = paddnum;
            if (dtsource != null)
            {
                //startindex = Convert.ToInt32(dtsource.Rows[0][prime_key]);//最小ID
                //endindex = Convert.ToInt32(dtsource.Rows[dtsource.Rows.Count - 1][prime_key]);//最大ID
                if (dtsource.Rows.Count <= paddingnum)
                {
                    if (wherestr == "")
                    {
                        if (orderzd == "")
                        {
                            sql = "select top " + paddingnum + " * from " + tablename;//house_recommendationlist
                        }
                        else
                        {
                            sql = "select top " + paddingnum + " * from " + tablename + " order by " + orderzd + " " + myorders;
                        }
                    }
                    else
                    {
                        if (orderzd == "")
                        {
                            sql = "select top " + paddingnum + " * from " + tablename;//house_recommendationlist
                        }
                        else
                        {
                            sql = "select top " + paddingnum + " * from " + tablename + " where " + wherestr + " order by " + orderzd + " " + myorders;
                        }
                    }
                }
                else
                {
                    if ((dtsource.Rows.Count - ((currpageindex - 1) * paddingnum)) <= paddingnum)
                    {
                        if (wherestr.Length == 0)
                        {
                            if (orderzd.Length == 0)
                            {
                                sql = "select * from " + tablename + " where " + prime_key + " >= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key];
                            }
                            else
                            {

                                if (myorders.ToString() == "asc")
                                {
                                    sql = "select * from " + tablename + " where " + prime_key + " >= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                                else
                                {
                                    sql = "select * from " + tablename + " where " + prime_key + " <= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                            }
                        }
                        else
                        {
                            if (orderzd.Length == 0)
                            {
                                if (myorders.ToString() == "asc")
                                {
                                    sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " >= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key];
                                }
                            }
                            else
                            {
                                if (myorders.ToString() == "asc")
                                {
                                    sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " >= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                                else
                                {
                                    sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " <= " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                            }
                        }
                    }
                    else
                    {
                        if (wherestr.Length == 0)
                        {
                            if (orderzd.Length == 0)
                            {
                                sql = "select * from " + tablename + " where " + prime_key + " between " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " and " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key];
                            }
                            else
                            {
                                if (myorders.ToString() == "asc")
                                {
                                   
                                  
                                    sql = "select * from " + tablename + " where " + prime_key + " between " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " and " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                                else
                                {
                                    sql = "select * from " + tablename + " where " + prime_key + " between " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key] + " and " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                            }
                        }
                        else
                        {
                            if (orderzd.Length == 0)
                            {
                                sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " between " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " and " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key];
                            }
                            else
                            {
                                if (myorders.ToString() == "asc")
                                {
                                   
                                  
                                    sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " between " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " and " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                                else
                                {
                                    sql = "select * from " + tablename + " where " + wherestr + " and " + prime_key + " between " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key] + " and " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " order by " + orderzd + " " + myorders;
                                }
                            }
                        }
                        //sql = "select * from " + tablename + " where " + prime_key + " between " + dtsource.Rows[paddingnum * (currpageindex - 1)][prime_key] + " and " + dtsource.Rows[(paddingnum * currpageindex) - 1][prime_key];

                    }
                }
                dt = DBUtility.DbHelperSQL.Query(sql).Tables[0];

            }
            return dt;
        }