Access 通用访问类 OleDbHelper

最近在做一个项目数据库用的是Access,第一次使用Access数据库，刚开始做有些不顺，数据库的操作和SqlServer稍有些不同，而异常跟踪得到的信息也没有什么意义，经过几天的反复寻找问题，总算解决了一些问题，为了访问Access 数据库，我写了一个用于专门访问的类来操作数据库，其中包括，执行数据库命令，返回 DataSet，返回单条记录，返回DataReader，通用分页方法等几个常用的的操作方法。请各位提出意见，以便我完善这个类。虽是参考SqlHelper 但是比其简单的多，所有的代码如下：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.Common;
using System.Data.OleDb;

namespace Common
{
    /**//// <summary>
    /// OleDb 书库访问类
    /// </summary>
    public static class OleDbHelper
    {
        /**//// <summary>
        /// Access 的数据库连接字符串格式.
        /// </summary>
        public const string ACCESS_CONNECTIONSTRING_TEMPLATE = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};";

        // Hashtable to store cached parameters
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

        /**//// <summary>
        /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
        /// </summary>
        /// <param name="connString"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static int ExecuteNonQuery(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();

            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /**//// <summary>
        /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
        /// </summary>
        /// <param name="conn"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static int ExecuteNonQuery(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /**//// <summary>
        /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
        /// </summary>
        /// <param name="trans"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static int ExecuteNonQuery(OleDbTransaction trans, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms, ConnectionActionType.None);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }

        /**//// <summary>
        /// 将 System.Data.OleDb.OleDbCommand.CommandText 发送到 System.Data.OleDb.OleDbCommand.Connection 并生成一个 System.Data.OleDb.OleDbDataReader.
        /// </summary>
        /// <param name="connString"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static OleDbDataReader ExecuteReader(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            OleDbConnection conn = new OleDbConnection(connString);
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
                OleDbDataReader rdr = cmd.ExecuteReader();
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }

        /**//// <summary>
        /// 将 System.Data.OleDb.OleDbCommand.CommandText 发送到 System.Data.OleDb.OleDbCommand.Connection 并生成一个 System.Data.OleDb.OleDbDataReader.
        /// </summary>
        /// <param name="conn"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static OleDbDataReader ExecuteReader(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
                OleDbDataReader rdr = cmd.ExecuteReader();
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }

        /**//// <summary>
        /// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行.
        /// </summary>
        /// <param name="connString"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static object ExecuteScalar(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
                object val = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return val;
            }
        }

        /**//// <summary>
        /// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行.
        /// </summary>
        /// <param name="conn"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static object ExecuteScalar(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }

        /**//// <summary>
        /// 执行查询，并返回查询所返回的结果数据集.
        /// </summary>
        /// <param name="connString"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static DataSet ExecuteDataset(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
                OleDbDataAdapter da = new OleDbDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds);
                cmd.Parameters.Clear();
                return ds;
            }
        }

        /**//// <summary>
        /// 执行查询，并返回查询所返回的结果数据集.
        /// </summary>
        /// <param name="conn"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static DataSet ExecuteDataset(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
        {
            OleDbCommand cmd = new OleDbCommand();
            PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
            OleDbDataAdapter da = new OleDbDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            cmd.Parameters.Clear();
            return ds;
        }

        /**//// <summary>
        /// 缓存查询的 OleDb 参数对象.
        /// </summary>
        /// <param name="cacheKey"></param>
        /// <param name="cmdParms"></param>
        public static void CacheParameters(string cacheKey, params OleDbParameter[] cmdParms)
        {
            parmCache[cacheKey] = cmdParms;
        }

        /**//// <summary>
        /// 从缓存获取指定的参数对象数组.
        /// </summary>
        /// <param name="cacheKey"></param>
        /// <returns></returns>
        public static OleDbParameter[] GetCachedParameters(string cacheKey)
        {
            OleDbParameter[] cachedParms = (OleDbParameter[])parmCache[cacheKey];

            if (cachedParms == null)
                return null;

            OleDbParameter[] clonedParms = new OleDbParameter[cachedParms.Length];
            for (int i = 0, j = cachedParms.Length; i < j; i++)
                clonedParms[i] = (OleDbParameter)((ICloneable)cachedParms[i]).Clone();

            return clonedParms;
        }

        /**//// <summary>
        /// 准备命令对象.
        /// </summary>
        /// <param name="cmd"></param>
        /// <param name="conn"></param>
        /// <param name="trans"></param>
        /// <param name="cmdType"></param>
        /// <param name="cmdText"></param>
        /// <param name="cmdParms"></param>
        /// <param name="connActionType"></param>
        private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, CommandType cmdType, string cmdText, OleDbParameter[] cmdParms, ConnectionActionType connActionType)
        {
            if (connActionType == ConnectionActionType.Open)
            {
                conn.Open();
            }
            else
            {
                if (conn.State != ConnectionState.Open)
                    conn.Open();
            }

            cmd.Connection = conn;
            cmd.CommandText = cmdText;

            if (trans != null)
                cmd.Transaction = trans;

            cmd.CommandType = cmdType;

            if (cmdParms != null)
            {
                foreach (OleDbParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }
        /**//// <summary>
        /// 统一分页显示数据记录
        /// </summary>
        /// <param name="connString">数据库连接字符串</param>
        /// <param name="pageIndex">当前页码</param>
        /// <param name="pageSize">每页显示的条数</param>
        /// <param name="fileds">显示的字段</param>
        /// <param name="table">查询的表格</param>
        /// <param name="where">查询的条件</param>
        /// <param name="order">排序的规则</param>
        /// <param name="pageCount">out：总页数</param>
        /// <param name="recordCount">out：总条数</param>
        /// <param name="id">表的主键</param>
        /// <returns>返回DataTable集合</returns>
        public static DataTable ExecutePager(string connString, int pageIndex, int pageSize, string fileds, string table, string where, string order, out int pageCount, out int recordCount, string id)
        {
            if (pageIndex < 1) pageIndex = 1;
            if (pageSize < 1) pageSize = 10;
            if (string.IsNullOrEmpty(fileds)) fileds = "*";
            if (string.IsNullOrEmpty(order)) order = "ID desc";
            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                string myVw = string.Format(" {0} ", table);
                string sqlText = string.Format(" select count(0) as recordCount from {0} {1}", myVw, where);
                OleDbCommand cmdCount = new OleDbCommand(sqlText, conn);
                if (conn.State == ConnectionState.Closed)
                    conn.Open();
                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, fileds, myVw, where, order), 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, fileds, myVw, "where 1=2", order), 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, id, myVw, where, order), pageUpperBound, conn);
                    cmdRecord = new OleDbCommand(string.Format("select {0} from {1} where {4} in ({2}) order by {3} ", fileds, myVw, recordIDs, order, id), conn);

                }
                OleDbDataAdapter dataAdapter = new OleDbDataAdapter(cmdRecord);
                DataTable dt = new DataTable();
                dataAdapter.Fill(dt);
                return dt;
            }
        }

        private static string RecordID(string query, int passCount, OleDbConnection conn)
        {
            OleDbCommand cmd = new OleDbCommand(query, conn);
            string result = string.Empty;
            using (IDataReader dr = cmd.ExecuteReader())
            {
                while (dr.Read())
                {
                    if (passCount < 1)
                    {
                        result += "," + dr.GetInt32(0);
                    }
                    passCount--;
                }
            }
            return result.Substring(1);
        }

        /**//// <summary>
        /// 连接操作类型枚举.
        /// </summary>
        enum ConnectionActionType
        {
            None = 0,
            AutoDetection = 1,
            Open = 2
        }
    }
}