本文实例讲述了C#实现Access通用访问类OleDbHelper。分享给大家供大家参考，具体如下：
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
}
}
}
希望本文所述对大家C#程序设计有所帮助。
dy("nrwz");
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