.net使用access数据库 为什么刷新网站时候老是报错

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懂视网 时间：2022-04-12 02:57

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data;using System.Data.OleDb;namespace JonseTool{ public abstract class AccessHelper { // string s = Application.StartupPath.Replace(@inDebug

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Data;
using System.Data.OleDb;

namespace JonseTool
{
 public abstract class AccessHelper
 {
  // string s = Application.StartupPath.Replace(@"inDebug", "") + @"Data#test.mdb";
  ////JonseTool.AccessHelper.ConnString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + s + @";Persist Security Info=false;User Id=admin;Password=";
  //JonseTool.AccessHelper.ConnString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + s + @";";

 public static string _sConnString = string.Empty;
 public static string ConnString
 {
  get{return _sConnString;}
  set{_sConnString = value;}
 }

 public static bool TestConn(string sConnStr="")
 {
  OleDbConnection myConn = null;
  bool bResult = false;
  try
  {
  if (string.IsNullOrEmpty(sConnStr)) sConnStr = _sConnString;
  myConn = new OleDbConnection(_sConnString);
  myConn.Open();
  }
  catch (Exception ex)
  {
  }
  finally
  {
  if (myConn != null && myConn.State.ToString() == "Open")
   bResult = true;
  }

  myConn.Close();

  return bResult;
 }

 public static DataTable GetDataTable(out string sErr, string sSQL,string sConnStr="",params OleDbParameter[] cmdParams)
 {
  DataTable dt = null;
  sErr = string.Empty;

  if (string.IsNullOrEmpty(sConnStr)) sConnStr = _sConnString;

  OleDbConnection accConn = null;
  try
  {
  accConn = new OleDbConnection(sConnStr);
  OleDbCommand accCmd = new OleDbCommand(sSQL, accConn);
  accConn.Open();

  if (cmdParams != null) 
  {
   foreach (OleDbParameter parm in cmdParams)
   accCmd.Parameters.Add(parm); 
  }
 
  OleDbDataAdapter adapter = new OleDbDataAdapter(accCmd);
  dt = new DataTable();
  adapter.Fill(dt);
  accConn.Close();
  }
  catch (Exception ex)
  {
  sErr = ex.Message;
  }
  return dt;
 }

 // 取dataset 
 public static DataSet GetDataSet(out string sError, string sSQL, string sConnStr = "", params OleDbParameter[] cmdParams)
 {
  DataSet ds = null;
  sError = string.Empty;
  try
  {
  if (string.IsNullOrEmpty(sConnStr)) sConnStr = _sConnString;

  OleDbConnection conn = new OleDbConnection(sConnStr);
  conn.Open();
  OleDbCommand cmd = new OleDbCommand();
  cmd.Connection = conn;
  cmd.CommandText = sSQL;

  if (cmdParams != null)
  {
   foreach (OleDbParameter parm in cmdParams)
   cmd.Parameters.Add(parm);
  }

  OleDbDataAdapter dapter = new OleDbDataAdapter(cmd);
  ds = new DataSet();
  dapter.Fill(ds);
  }
  catch (Exception ex)
  {
  sError = ex.Message;
  }
  return ds;
 }

 // 取某个单一的元素 
 public static object GetSingle(out string sError, string sSQL,string sConnStr)
 {
  DataTable dt = GetDataTable(out sError, sSQL,sConnStr);
  if (dt != null && dt.Rows.Count > 0)
  {
  return dt.Rows[0][0];
  }

  return null;
 }

 // 取最大的ID 
 public static Int32 GetMaxID(out string sError, string sKeyField, string sTableName,string sConnStr=null)
 {
  DataTable dt = GetDataTable(out sError, "select iif(isnull(max([" + sKeyField + "])),0,max([" + sKeyField + "])) as MaxID from [" + sTableName + "]", sConnStr);
  if (dt != null && dt.Rows.Count > 0)
  {
  return Convert.ToInt32(dt.Rows[0][0].ToString());
  }

  return 0;
 }

 // 执行 insert,update,delete 动作，也可以使用事务 
 public static bool UpdateData(out string sError, string sSQL,string sConnStr="",OleDbParameter[] cmdParams = null, bool bUseTransaction = false)
 {
  int iResult = 0;
  sError = string.Empty;
  if (string.IsNullOrEmpty(sConnStr)) sConnStr = _sConnString;

  if (!bUseTransaction)
  {
  try
  {
   OleDbConnection conn = new OleDbConnection(sConnStr);
   if (conn.State != ConnectionState.Open)
   conn.Open();
   OleDbCommand cmd = new OleDbCommand();
   cmd.Connection = conn;
   cmd.CommandText = sSQL;

   if (cmdParams != null)
   {
   foreach (OleDbParameter parm in cmdParams)
    cmd.Parameters.Add(parm);
   }

   iResult = cmd.ExecuteNonQuery();
  }
  catch (Exception ex)
  {
   sError = ex.Message;
   iResult = -1;
  }
  }
  else // 使用事务 
  {
  OleDbTransaction trans = null;
  try
  {
   OleDbConnection conn = new OleDbConnection(sConnStr);
   if (conn.State != ConnectionState.Open)
   conn.Open();
   trans = conn.BeginTransaction();
   OleDbCommand cmd = new OleDbCommand();
   cmd.Connection = conn;
   cmd.CommandText = sSQL;

   if (cmdParams != null)
   {
   foreach (OleDbParameter parm in cmdParams)
    cmd.Parameters.Add(parm);
   }

   cmd.Transaction = trans;
   iResult = cmd.ExecuteNonQuery();
   trans.Commit();
  }
  catch (Exception ex)
  {
   sError = ex.Message;
   iResult = -1;
   trans.Rollback();
  }
  }

  return iResult > 0;
 } 
 
 }
}

示意图：

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