1 try
 2             {
 3                 //_dbConnection是全局的实例属性DbConnection，在构造中初始化了
 4                 //注意：此处使用全局的实例属性DbConnection，就会出现标题的异常
 5                 var cmd = _dbConnection.CreateCommand();
 6                 cmd.CommandText = sql;
 7                 cmd.CommandType = System.Data.CommandType.Text;
 8                 if (dbParameterCollection != null)
 9                     foreach (var item in dbParameterCollection)
10                     {
11                         cmd.Parameters.Add(item);
12                     }
13                 if (_dbTrans != null)
14                     cmd.Transaction = _dbTrans;
15                 if (_dbConnection != null && _dbConnection.State != System.Data.ConnectionState.Open)
16                 {
17                     _dbConnection.Open();
18                 }
19                 return cmd.ExecuteReader();
20             }
21             catch (Exception ex)
22             {
23                 throw;
24             }

 1             var arr = Enumerable.Range(0, 49).ToArray();
 2             using (var db = new DBHelper())
 3             {
 4                 //using (var tran = new Trans(db))
 5                 //{
 6                     try
 7                     {
 8                         Parallel.For(0, 49, (i) =>
 9                         {
10                             var item = arr[i];
11                             Console.WriteLine("开始执行：{0}", item);
12                             //3.得到此设备下所有点信息
13                             var tagInfo = db.Query<Books>(string.Format("select * from books where id='{0}'", Guid.NewGuid()));
14                         });
15                     }
16                     catch (Exception ex) { }
17                 //}
18             }
19             Console.WriteLine("123");
20 
21             Console.ReadLine();

 1         public IEnumerable<T> Query<T>(string sql, IEnumerable<DbParameter> dbParameterCollection = null) where T : class,new()
 2         {
 3             var reader = ExecDataReader(sql, dbParameterCollection);
 4 
 5             try
 6             {
 7                 var ls = new List<T>();
 8 
 9                 return ls;
10             }
11             catch (Exception ex)
12             {
13 
14                 throw new Exception("DataReader映射为实体时出错！", ex);
15             }
16             finally
17             {
18                 tools.CloseIDataReader(reader);
19             }
20         }