using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.OleDb;
using System.Collections;
/// <summary>
/// AcceHelper 的摘要說明
/// </summary>
public static class AccessHelper
{
  //數(shù)據(jù)庫連接字符串
  public static readonly string conn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + HttpContext.Current.Request.PhysicalApplicationPath + System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
  // 用于緩存參數(shù)的HASH表
  private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());
  /// <summary>
  /// 給定連接的數(shù)據(jù)庫用假設(shè)參數(shù)執(zhí)行一個sql命令（不返回數(shù)據(jù)集）
  /// </summary>
  /// <param name="connectionString">一個有效的連接字符串</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>執(zhí)行命令所影響的行數(shù)</returns>
  public static int ExecuteNonQuery(string connectionString, string cmdText, params OleDbParameter[] commandParameters)
  {
    OleDbCommand cmd = new OleDbCommand();
    using (OleDbConnection conn = new OleDbConnection(connectionString))
    {
      PrepareCommand(cmd, conn, null, cmdText, commandParameters);
      int val = cmd.ExecuteNonQuery();
      cmd.Parameters.Clear();
      return val;
    }
  }
  /// <summary>
  /// 用現(xiàn)有的數(shù)據(jù)庫連接執(zhí)行一個sql命令（不返回數(shù)據(jù)集）
  /// </summary>
  /// <remarks>
  ///舉例: 
  /// int result = ExecuteNonQuery(connString, "PublishOrders", new OleDbParameter("@prodid", 24));
  /// </remarks>
  /// <param name="conn">一個現(xiàn)有的數(shù)據(jù)庫連接</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>執(zhí)行命令所影響的行數(shù)</returns>
  public static int ExecuteNonQuery(OleDbConnection connection, string cmdText, params OleDbParameter[] commandParameters)
  {
    OleDbCommand cmd = new OleDbCommand();
    PrepareCommand(cmd, connection, null, cmdText, commandParameters);
    int val = cmd.ExecuteNonQuery();
    cmd.Parameters.Clear();
    return val;
  }
  /// <summary>
  ///使用現(xiàn)有的SQL事務(wù)執(zhí)行一個sql命令（不返回數(shù)據(jù)集）
  /// </summary>
  /// <remarks>
  ///舉例: 
  /// int result = ExecuteNonQuery(trans, "PublishOrders", new OleDbParameter("@prodid", 24));
  /// </remarks>
  /// <param name="trans">一個現(xiàn)有的事務(wù)</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>執(zhí)行命令所影響的行數(shù)</returns>
  public static int ExecuteNonQuery(OleDbTransaction trans, string cmdText, params OleDbParameter[] commandParameters)
  {
    OleDbCommand cmd = new OleDbCommand();
    PrepareCommand(cmd, trans.Connection, trans, cmdText, commandParameters);
    int val = cmd.ExecuteNonQuery();
    cmd.Parameters.Clear();
    return val;
  }
  /// <summary>
  /// 用執(zhí)行的數(shù)據(jù)庫連接執(zhí)行一個返回數(shù)據(jù)集的sql命令
  /// </summary>
  /// <remarks>
  /// 舉例: 
  /// OleDbDataReader r = ExecuteReader(connString, "PublishOrders", new OleDbParameter("@prodid", 24));
  /// </remarks>
  /// <param name="connectionString">一個有效的連接字符串</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>包含結(jié)果的讀取器</returns>
  public static OleDbDataReader ExecuteReader(string connectionString, string cmdText, params OleDbParameter[] commandParameters)
  {
    //創(chuàng)建一個SqlCommand對象
    OleDbCommand cmd = new OleDbCommand();
    //創(chuàng)建一個SqlConnection對象
    OleDbConnection conn = new OleDbConnection(connectionString);
    //在這里我們用一個try/catch結(jié)構(gòu)執(zhí)行sql文本命令/存儲過程，因為如果這個方法產(chǎn)生一個異常我們要關(guān)閉連接，因為沒有讀取器存在，
    //因此commandBehaviour.CloseConnection 就不會執(zhí)行
    try
    {
      //調(diào)用 PrepareCommand 方法，對 SqlCommand 對象設(shè)置參數(shù)
      PrepareCommand(cmd, conn, null, cmdText, commandParameters);
      //調(diào)用 SqlCommand 的 ExecuteReader 方法
      OleDbDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
      //清除參數(shù)
      cmd.Parameters.Clear();
      return reader;
    }
    catch
    {
      //關(guān)閉連接，拋出異常
      conn.Close();
      throw;
    }
  }
  /// <summary>
  /// 返回一個DataSet數(shù)據(jù)集
  /// </summary>
  /// <param name="connectionString">一個有效的連接字符串</param>
  /// <param name="cmdText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>包含結(jié)果的數(shù)據(jù)集</returns>
  public static DataSet ExecuteDataSet(string connectionString, string cmdText, params OleDbParameter[] commandParameters)
  {
    //創(chuàng)建一個SqlCommand對象，并對其進(jìn)行初始化
    OleDbCommand cmd = new OleDbCommand();
    using (OleDbConnection conn = new OleDbConnection(connectionString))
    {
      PrepareCommand(cmd, conn, null, cmdText, commandParameters);
      //創(chuàng)建SqlDataAdapter對象以及DataSet
      OleDbDataAdapter da = new OleDbDataAdapter(cmd);
      DataSet ds = new DataSet();
      try
      {
        //填充ds
        da.Fill(ds);
        // 清除cmd的參數(shù)集合 
        cmd.Parameters.Clear();
        //返回ds
        return ds;
      }
      catch
      {
        //關(guān)閉連接，拋出異常
        conn.Close();
        throw;
      }
    }
  }
  /// <summary>
  /// 用指定的數(shù)據(jù)庫連接字符串執(zhí)行一個命令并返回一個數(shù)據(jù)集的第一列
  /// </summary>
  /// <remarks>
  ///例如: 
  /// Object obj = ExecuteScalar(connString, "PublishOrders", new OleDbParameter("@prodid", 24));
  /// </remarks>
  ///<param name="connectionString">一個有效的連接字符串</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>用 Convert.To{Type}把類型轉(zhuǎn)換為想要的 </returns>
  public static object ExecuteScalar(string connectionString, string cmdText, params OleDbParameter[] commandParameters)
  {
    OleDbCommand cmd = new OleDbCommand();
    using (OleDbConnection connection = new OleDbConnection(connectionString))
    {
      PrepareCommand(cmd, connection, null, cmdText, commandParameters);
      object val = cmd.ExecuteScalar();
      cmd.Parameters.Clear();
      return val;
    }
  }
  /// <summary>
  /// 用指定的數(shù)據(jù)庫連接執(zhí)行一個命令并返回一個數(shù)據(jù)集的第一列
  /// </summary>
  /// <remarks>
  /// 例如: 
  /// Object obj = ExecuteScalar(connString, "PublishOrders", new OleDbParameter("@prodid", 24));
  /// </remarks>
  /// <param name="conn">一個存在的數(shù)據(jù)庫連接</param>
  /// <param name="commandText">存儲過程名稱或者sql命令語句</param>
  /// <param name="commandParameters">執(zhí)行命令所用參數(shù)的集合</param>
  /// <returns>用 Convert.To{Type}把類型轉(zhuǎn)換為想要的 </returns>
  public static object ExecuteScalar(OleDbConnection connection, string cmdText, params OleDbParameter[] commandParameters)
  {
    OleDbCommand cmd = new OleDbCommand();
    PrepareCommand(cmd, connection, null, cmdText, commandParameters);
    object val = cmd.ExecuteScalar();
    cmd.Parameters.Clear();
    return val;
  }
  /// <summary>
  /// 將參數(shù)集合添加到緩存
  /// </summary>
  /// <param name="cacheKey">添加到緩存的變量</param>
  /// <param name="cmdParms">一個將要添加到緩存的sql參數(shù)集合</param>
  public static void CacheParameters(string cacheKey, params OleDbParameter[] commandParameters)
  {
    parmCache[cacheKey] = commandParameters;
  }
  /// <summary>
  /// 找回緩存參數(shù)集合
  /// </summary>
  /// <param name="cacheKey">用于找回參數(shù)的關(guān)鍵字</param>
  /// <returns>緩存的參數(shù)集合</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 =(OleDbParameter[])((ICloneable)cachedParms).Clone();
    return clonedParms;
  }
  /// <summary>
  /// 準(zhǔn)備執(zhí)行一個命令
  /// </summary>
  /// <param name="cmd">sql命令</param>
  /// <param name="conn">Sql連接</param>
  /// <param name="trans">Sql事務(wù)</param>
  /// <param name="cmdText">命令文本,例如：Select * from Products</param>
  /// <param name="cmdParms">執(zhí)行命令的參數(shù)</param>
  private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, string cmdText, OleDbParameter[] cmdParms)
  {
    //判斷連接的狀態(tài)。如果是關(guān)閉狀態(tài)，則打開
    if (conn.State != ConnectionState.Open)
      conn.Open();
    //cmd屬性賦值
    cmd.Connection = conn;
    cmd.CommandText = cmdText;
    //是否需要用到事務(wù)處理
    if (trans != null)
      cmd.Transaction = trans;
    cmd.CommandType = CommandType.Text;
    //添加cmd需要的存儲過程參數(shù)
    if (cmdParms != null)
    {
      foreach (OleDbParameter parm in cmdParms)
        cmd.Parameters.Add(parm);
    }
  }
}