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  • ACCESS高效分页

    由于Access数据库内没有存储过程一说.
    那么实现它的分页上效率问题一直都是麻烦事..下面一段代码,相当来说算了很高效的了.
    如果有什么更好的方法,请多指教! 谢谢!
    调用方法

    程序代码 程序代码
    string strSql = " Select P.ProductID,P.ProClassID,P.ProductName,P.ProFlag,P.DateTime,P.ProductImage,C.ProClassName,C.ProClassKey,C.ProClassDes FROM ProductInfo P  " +
                                    " LEFT JOIN ProClass C ON P.ProClassID=C.ProClassID ";
                    string strShow = " ProductID,ProductName,DateTime,ProductImage,ProFlag,ProClassName,ProClassKey,ProClassDes ";
                    return ClassFile.AccessHelper.ExecutePager(PageIndex, PageSize, "ProductID", strShow, strSql, strWhere, " ProductID DESC ", out PageCount, out RecordCount);
    程序代码 程序代码
    /// <summary>
            /// 分页使用
            /// </summary>
            /// <param name="query"></param>
            /// <param name="passCount"></param>
            /// <returns></returns>
            private static string recordID(string query, int passCount)
            {
                using (OleDbConnection m_Conn = new OleDbConnection(ConnectionString))
                {
                    m_Conn.Open();
                    OleDbCommand cmd = new OleDbCommand(query, m_Conn);
                    string result = string.Empty;
                    using (OleDbDataReader dr = cmd.ExecuteReader())
                    {
                        while (dr.Read())
                        {
                            if (passCount < 1)
                            {
                                result += "," + dr.GetInt32(0);
                            }
                            passCount--;
                        }
                    }
                    m_Conn.Close();
                    m_Conn.Dispose();
                    return result.Substring(1);
                }
            }
            /// <summary>
            /// ACCESS高效分页
            /// </summary>
            /// <param name="pageIndex">当前页码</param>
            /// <param name="pageSize">分页容量</param>
            /// <param name="strKey">主键</param>
            /// <param name="showString">显示的字段</param>
            /// <param name="queryString">查询字符串,支持联合查询</param>
            /// <param name="whereString">查询条件,若有条件限制则必须以where 开头</param>
            /// <param name="orderString">排序规则</param>
            /// <param name="pageCount">传出参数:总页数统计</param>
            /// <param name="recordCount">传出参数:总记录统计</param>
            /// <returns>装载记录的DataTable</returns>
            public static DataTable ExecutePager(int pageIndex, int pageSize, string strKey,string showString, string queryString, string whereString, string orderString, out int pageCount, out int recordCount)
            {
                if (pageIndex < 1) pageIndex = 1;
                if (pageSize < 1) pageSize = 10;
                if (string.IsNullOrEmpty(showString)) showString = "*";
                if (string.IsNullOrEmpty(orderString)) orderString = strKey+" asc ";
                using (OleDbConnection m_Conn = new OleDbConnection(ConnectionString))
                {
                    m_Conn.Open();
                    string myVw = string.Format(" ( {0} ) tempVw ", queryString);
                    OleDbCommand cmdCount = new OleDbCommand(string.Format(" select count(*) as recordCount from {0} {1}", myVw, whereString), m_Conn);

                    recordCount = Convert.ToInt32(cmdCount.ExecuteScalar());

                    if ((recordCount % pageSize) > 0)
                        pageCount = recordCount / pageSize + 1;
                    else
                        pageCount = recordCount / pageSize;
                    OleDbCommand cmdRecord;
                    if (pageIndex == 1)//第一页
                    {
                        cmdRecord = new OleDbCommand(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageSize, showString, myVw, whereString, orderString), m_Conn);
                    }
                    else if (pageIndex > pageCount)//超出总页数
                    {
                        cmdRecord = new OleDbCommand(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageSize, showString, myVw, "where 1=2", orderString), m_Conn);
                    }
                    else
                    {
                        int pageLowerBound = pageSize * pageIndex;
                        int pageUpperBound = pageLowerBound - pageSize;
                        string recordIDs = recordID(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageLowerBound, strKey, myVw, whereString, orderString), pageUpperBound);
                        cmdRecord = new OleDbCommand(string.Format("select {0} from {1} where {2} in ({3}) order by {4} ", showString, myVw,strKey, recordIDs, orderString), m_Conn);

                    }
                    OleDbDataAdapter dataAdapter = new OleDbDataAdapter(cmdRecord);
                    DataTable dt = new DataTable();
                    dataAdapter.Fill(dt);
                    m_Conn.Close();
                    m_Conn.Dispose();
                return dt;
                }
            }
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  • 原文地址:https://www.cnblogs.com/sontin/p/1929793.html
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