System.Data.OleDb.OleDbException: 未指定的错误

Question

    public OleDbDataReader ReadRow(OleDbConnection myConnection, string strSql)
    {
        myConnection = new OleDbConnection(connectionString);
        myConnection.Open();
        OleDbCommand myCommand = new OleDbCommand(strSql, myConnection);
        OleDbDataReader dr = myCommand.ExecuteReader();
        if (dr.Read())
        {
            myCommand.Dispose();
            return dr;
        }
        else
        {
            myCommand.Dispose();
            return null;
        }
    }
myConnection.Open();-----错误被定格在这行
就是网页来回测试一段时间之后就出现这情况，上次问了只能在调用函数的时候关闭连接 不过一段时间还是出现这错误
获得OleDbDataReader 关闭连接的问题网上也找了好几天了 一直没有解决  反正就是一段时间就出现这个问题 重新开启之后就又可以了
连接池满了应该 那应该这样正确关闭呢 望高手指点

Answer 1

没见你的调用方法，没见你 close connection

Answer 2

    protected void IPInsert()
    {
        IPAddress ipAddress = new IPAddress();
        string user_ip = ipAddress.GetIPAddress();
        string SelectIPSql = "Select IpAddress From ipinfo Where IpAddress='" + user_ip + "'";
        OleDbDataReader dr = QinMiData.ReadRow(myConnection, SelectIPSql);
        if (dr != null)
        {
            string UpdateIPSql = "Update ipinfo Set AddTime='" + DateTime.Now + "' where IpAddress='" + user_ip + "'";
            QinMiData.ExecuteSql(UpdateIPSql);
            dr.Close();
            myConnection.Close();
            myConnection.Dispose();
        }
        else
        {
            string InsertIPSql = "Insert into ipinfo(IpAddress,AddTime) values('" + user_ip + "','" + DateTime.Now + "')";
            QinMiData.ExecuteSql(InsertIPSql);
            dr.Close();
            myConnection.Close();
            myConnection.Dispose();
        }
    }
比如上面这个 我都关闭了的 很奇怪一段时间之后就不行了

Answer 3

另外我的是ACCESS数据库  不知道是不是也有影响~~

Answer 4

connectionString里面有值么，输出一下看看，或者换个固定的路径试试

Answer 5

public OleDbDataReader ReadRow(OleDbConnection myConnection, string strSql)
    {
        myConnection = new OleDbConnection(connectionString);  //把这行注释掉试一下。
        myConnection.Open();

Answer 6

恩 都可以正常运行的
主要就是一段时间的操作之后就出现那个问题 指示的错误就是OPEN那里。。

Answer 7

我想问题出在你试图返回一个reader,这样做行不通。reader是同步操作数据库，增量读取数据（读完一条数据接着下一条，无法再返回上一条数据），所以你返回一个reader这样做是毫无意义的。返回一个DataSet object是正道。

Answer 8

protected void IPInsert()
    {
        IPAddress ipAddress = new IPAddress();
        string user_ip = ipAddress.GetIPAddress();
        string SelectIPSql = "Select IpAddress From ipinfo Where IpAddress='" + user_ip + "'";
OleDbConnection con=new OleDBConnection();
con.Open();
OleDbCommand cmd=new OleDbCommand(SelectIPSql,con);
        OleDbDataReader dr = cmd.ExecuteNonQuery();
        if (!dr.HasRows)
        {
            string UpdateIPSql = "Update ipinfo Set AddTime='" + DateTime.Now + "' where IpAddress='" + user_ip + "'";
            QinMiData.ExecuteSql(UpdateIPSql);
            //dr.Close();
            //myConnection.Close();
            //myConnection.Dispose();
        }
        else
        {
            string InsertIPSql = "Insert into ipinfo(IpAddress,AddTime) values('" + user_ip + "','" + DateTime.Now + "')";
            QinMiData.ExecuteSql(InsertIPSql);
            //dr.Close();
            //myConnection.Close();
            //myConnection.Dispose();
        }
dr.Close();
con.Close();
    }改成这样吧。

Answer 9

OleDbConnection con=new OleDBConnection("你的连接串");不好意思，忘了。还有你的这个myConnection，最好要用的时候创建，用完即销毁，不要使用类似全局变量的这种方式。

Answer 10

建议用两个独立的方法，不要把read和update放在一个方法里。protected bool HasIpExisted(string userIp)
{
    bool hasIpExisted = false;    //define connection, command, reader
    
    myReader = myCommand.ExecuteReader();    hasIpExisted = myReader.HasRow;
 
    //close reader, connection
  
    return hasIpExisted;
}protected void UpdateIpAddress()
{
    string sqlCommand = string.Empty;    if ( HasIpExisted(ipAddress.GetIPAddress())) 
    {
        sqlCommand = "update xxxx xxxxx";
    }
    else 
    {
        sqlCommand = "insert into xxxxx";
    }    ..........
    ..........
   
}

Answer 11

myCommand.ExecuteReader(CommandBehavior.CloseConnection);

Answer 12

给你一个链接数据库方法类：/// <summary>
    /// DataAccess 数据访问类
    /// By Lify
    /// </summary>
    public class DataAccess:System.Web.UI.Page
    {
        #region 属性
        protected static OleDbConnection conn = new OleDbConnection();
        protected static OleDbCommand comm = new OleDbCommand();
        #endregion
        public DataAccess()
        {
            //init();
        }
        #region 内部函数 静态方法中不会执行DataAccess()构造函数        /// <summary>
        /// 打开数据库连接
        /// </summary>
        private static void openConnection()
        {
            if (conn.State == ConnectionState.Closed)
            {
                //SysConfig.ConnectionString 为系统配置类中连接字符串                conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\"" + System.Configuration.ConfigurationSettings.AppSettings.Get("AccessRoot").ToString() + "\";Persist Security Info=True";
                comm.Connection = conn;
                try
                {
                    conn.Open();
                }
                catch (Exception e)
                {
                    throw new Exception(e.Message);
                }
            }
        }        /// <summary>
        /// 关闭当前数据库连接
        /// </summary>
        private static void closeConnection()
        {
            if (conn.State == ConnectionState.Open)
                conn.Close();
            conn.Dispose();
            comm.Dispose();
        }
        #endregion        /// <summary>
        /// 执行Sql查询语句
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        public static void ExecuteSql(string sqlstr)
        {
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                comm.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
        }        /// <summary>
        /// 执行Sql查询语句并返回第一行的第一条记录,返回值为object 使用时需要拆箱操作 -> Unbox
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <returns>object 返回值 </returns>
        public static object ExecuteScalar(string sqlstr)
        {
            object obj = new object();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                obj = comm.ExecuteScalar();
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
            return obj;
        }        /// <summary>
        /// 执行Sql查询语句,同时进行事务处理
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        public static void ExecuteSqlWithTransaction(string sqlstr)
        {
            closeConnection();
            openConnection();            OleDbTransaction trans;
            trans = conn.BeginTransaction();
            comm.Transaction = trans;
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                comm.ExecuteNonQuery();
                trans.Commit();
            }
            catch
            {
                trans.Rollback();
            }
            finally
            {
                closeConnection();
            }
        }        /// <summary>
        /// 返回指定Sql语句的OleDbDataReader，请注意，在使用后请关闭本对象，同时将自动调用closeConnection()来关闭数据库连接
        /// 方法关闭数据库连接
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <returns>OleDbDataReader对象</returns>
        public static OleDbDataReader DataReader(string sqlstr)
        {
            OleDbDataReader dr = null;
            try
            {
                openConnection();
                comm.CommandText = sqlstr;
                comm.CommandType = CommandType.Text;
                dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                try
                {
                    dr.Close();
                    closeConnection();
                }
                catch
                {
                }
            }
            return dr;
        }
//待续 ......

Answer 13

续上.../// <summary>
        /// 返回指定Sql语句的OleDbDataReader，请注意，在使用后请关闭本对象，同时将自动调用closeConnection()来关闭数据库连接
        /// 方法关闭数据库连接
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <param name="dr">传入的ref DataReader 对象</param>
        public static void DataReader(string sqlstr, ref OleDbDataReader dr)
        {
            try
            {
                openConnection();
                comm.CommandText = sqlstr;
                comm.CommandType = CommandType.Text;
                dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                try
                {
                    if (dr != null && !dr.IsClosed)
                        dr.Close();
                }
                catch
                {
                }
                finally
                {
                    closeConnection();
                }
            }
        }        /// <summary>
        /// 返回指定Sql语句的DataSet
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <returns>DataSet</returns>
        public static DataSet DataSet(string sqlstr)
        {
            DataSet ds = new DataSet();
            OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(ds);
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
            return ds;
        }        /// <summary>
        /// 返回指定Sql语句的DataSet
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <param name="ds">传入的引用DataSet对象</param>
        public static void DataSet(string sqlstr, ref DataSet ds)
        {
            OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(ds);
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
        }
        /// <summary>
        /// 返回指定Sql语句的DataTable
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <returns>DataTable</returns>
        public static DataTable DataTable(string sqlstr)
        {
            OleDbDataAdapter da = new OleDbDataAdapter();
            DataTable Datatable = new DataTable();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(Datatable);
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
            return Datatable;
        }        /// <summary>
        /// 执行指定Sql语句,同时给传入DataTable进行赋值 
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <param name="dt">ref DataTable dt </param>
        public static void DataTable(string sqlstr, ref DataTable dt)
        {
            OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(dt);
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
        }        /// <summary>
        /// 返回指定Sql语句的DataView
        /// </summary>
        /// <param name="sqlstr">传入的Sql语句</param>
        /// <returns>DataView</returns>
        public static DataView DataView(string sqlstr)
        {
            OleDbDataAdapter da = new OleDbDataAdapter();
            DataView dv = new DataView();
            DataSet ds = new DataSet();
            try
            {
                openConnection();
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(ds);
                dv = ds.Tables[0].DefaultView;
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                closeConnection();
            }
            return dv;
        }
    }