ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.

今天調試一個監控程序，放到環境里發現不寫庫，於是給SQL執行類異常事件做了個日志，發現報：

ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.

左看右看，沒問題呀，后來才想起，using里沒有執行db.Open，打開數據庫連接。

 

    public class SQLHelper : IDisposable
    {
        private IntPtr handle;
        private readonly Component component = new Component();
        private bool disposed;
        private readonly string _connstr = Config.ConnectionString;

        #region 執行SQL語句，返回影響行數
        /// <summary>
        /// 執行查詢，返回影響行數
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public int iExecute(string sql)
        {
            int intTemp;
            try
            {
                using (var db = new SqlConnection(_connstr))
                {
                    db.Open();
                    var cmd = new SqlCommand(sql, db) {CommandType = CommandType.Text};
                    intTemp = cmd.ExecuteNonQuery();
                    db.Close();
                }
            }
            catch(Exception ex)
            {
                FileHelper.AppendFile("D:\\Log.txt", string.Format("{0}[{1}][{2}]",sql ,ex.Message,_connstr));
                intTemp = 0;
            }
            return intTemp;

        }
        #endregion

        #region 執行SQL語句，返回表結果
        /// <summary>
        /// 查詢返回DataSet
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public DataSet pExecute(string sql)
        {
            var ds = new DataSet();
            try
            {
                using (var db = new SqlConnection(_connstr))
                {
                    db.Open();
                    var dr = new SqlDataAdapter();
                    var cmd = new SqlCommand(sql, db) {CommandType = CommandType.Text};
                    dr.SelectCommand = cmd;
                    dr.Fill(ds);
                    ds = (ds.Tables.Count == 0) ? null : ds;
                    db.Close();
                }
            }
            catch{}
            return ds;
        }
        #endregion

        #region 執行存儲過程，返回查詢的表結果
        /// <summary>
        /// 執行存儲過程，返回查詢的表結果
        /// </summary>
        /// <param name="produceName"></param>
        /// <param name="param"></param>
        /// <returns></returns>
        public DataSet pExecute(string produceName, SqlParameter[] param)
        {
            var ds = new DataSet();
            try
            {
                using (var db = new SqlConnection(_connstr))
                {
                    db.Open();
                    var cmd = new SqlCommand {Connection = db,CommandType = CommandType.StoredProcedure,CommandText = produceName};
                    var dr = new SqlDataAdapter();
                    foreach (var t in param)
                    {
                        cmd.Parameters.Add(t);
                    }
                    dr.SelectCommand = cmd;
                    dr.Fill(ds);
                    db.Close();
                }
            }
            catch (Exception){}
            return ds;
            
        }
        #endregion

        #region 執行存儲過程，返回影響行數
        /// <summary>
        /// 執行存儲過程，返回影響行數
        /// </summary>
        /// <param name="produceName"></param>
        /// <param name="param"></param>
        /// <returns></returns>
        public int iExecute(string produceName, SqlParameter[] param)
        {
            int intTemp = 0;
            try
            {
                using (var db = new SqlConnection(_connstr))
                {
                    db.Open();
                    var cmd = new SqlCommand
                                  {
                                      Connection = db,
                                      CommandType = CommandType.StoredProcedure,
                                      CommandText = produceName
                                  };
                    foreach (var t in param)
                    {
                        cmd.Parameters.Add(t);
                    }
                    intTemp = cmd.ExecuteNonQuery();
                    db.Close();
                }
            }
            catch (Exception){}
            return intTemp;
        }
        #endregion

        #region Dispose實現
        public void Dispose()
        {
            try
            {
                Dispose(true);
                GC.SuppressFinalize(this);
            }
            catch (Exception)
            {
            }

        }
        private void Dispose(bool disposing)
        {
            if (!disposed)
            {
                if (disposing)
                {
                    component.Dispose();
                }
                CloseHandle(handle);
                handle = IntPtr.Zero;
                disposed = true;
            }
        }
        [System.Runtime.InteropServices.DllImport("Kernel32")]
        private extern static Boolean CloseHandle(IntPtr handle);
        #endregion


    }