SqlDataReader和SqlCommand

Question

我有下面的代码。

using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
   connection.Open();
   SqlCommand select = new SqlCommand("SELECT RTRIM(LTRIM(PART_NO)) AS PART_NO, record FROM [RMAData].[dbo].[IMPORTING_ORDER_EDI] WHERE sessionID = '" + Session.SessionID + "'", connection);

   SqlDataReader reader = select.ExecuteReader();

   if (reader.HasRows)
   {
      while (reader.Read())
      {
         if (!currentPart.IsActive)
         {
            // this part is not active, set the active flag in sql to 0
            SqlCommand update = new SqlCommand("UPDATE [RMAData].[dbo].[IMPORTING_ORDER_EDI] SET valid = 0, active = 0 WHERE record = " + reader["record"].ToString() + ";", connection);

            update.ExecuteNonQuery();
         }
         else
         {
            ///blah
         }
      }

      reader.Close();
   }
}

但这会导致以下例外..。

System.InvalidOperationException:已经有一个与此命令相关联的开放DataReader，必须先关闭。

我需要读取返回的每一行，对数据进行一些验证，并在必要时进行更新，然后继续到下一个记录。如果在循环遍历SqlCommand时不能使用reader.Read()，那么如何实现这一点呢？

Answer 1

另一种选择是不添加MultipleActiveResultSets=True --这样做会对性能造成很小的损失--如下所示：

using (SqlConnection connection = new ...))
{
   connection.Open();
   SqlCommand select = new SqlCommand(...);

   SqlDataReader reader = select.ExecuteReader();

   var toInactivate = new List<string>();

   if (reader.HasRows)
   {
      while (reader.Read())
      {
         if (!currentPart.IsActive)
         {
            toInactivate.Add(reader["record"].ToString());
         }
         else
         {
            ///blah
         }
      }

      reader.Close();
   }

   SqlCommand update = new SqlCommand("UPDATE ... SET valid = 0, active = 0 " +
       "WHERE record IN(" + string.Join(",", toInactivate) +  ");", connection);

   update.ExecuteNonQuery();
}

它具有在单个SQL语句中更新所有所需记录的优点。

当然，使用EF和Linq，整个过程会更加整洁。

Answer 2

可以像amending your connection string一样简单：

将MultipleActiveResultSets=True添加到连接字符串

Answer 3

您需要创建多个连接实例。

，因为通常只能对连接执行一个命令。

或

照@grantThomas的建议做

也可以使用多个连接，如下所示

using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
   connection.Open();
   SqlCommand select = new SqlCommand("SELECT RTRIM(LTRIM(PART_NO)) AS PART_NO, record FROM [RMAData].[dbo].[IMPORTING_ORDER_EDI] WHERE sessionID = '" + Session.SessionID + "'", connection);

   SqlDataReader reader = select.ExecuteReader();

   if (reader.HasRows)
   {
      while (reader.Read())
      {
         if (!currentPart.IsActive)
         {
            // this part is not active, set the active flag in sql to 0
            using (SqlConnection connection1 = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
           {
               SqlCommand update = new SqlCommand("UPDATE [RMAData].[dbo].[IMPORTING_ORDER_EDI] SET valid = 0, active = 0 WHERE record = " + reader["record"].ToString() + ";", connection1);


            update.ExecuteNonQuery();
           }
         }
         else
         {
            ///blah
         }
      }

      reader.Close();
   }
}