2

我有以下代码。

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();
   }
}

但这会导致以下异常...

System.InvalidOperationException：已经有一个打开的 DataReader 与此命令关联，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，然后继续下一条记录。如果我不能使用SqlCommandwhile 循环，我怎么能做到这一点reader.Read()？

4

3 回答 3

6

可以像修改连接字符串一样简单：

将 MultipleActiveResultSets=True 添加到连接字符串

于 2013-02-21T15:31:07.580 回答
3

您需要创建连接的多个实例。
因为通常只能针对连接执行一个命令
或

按照@grantThomas 的建议执行
或者您可以使用多个连接，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();
   }
}
于 2013-02-21T15:37:39.953 回答
3

另一种方法是不添加 MultipleActiveResultSets=True - 这样做会带来很小的性能损失 - 所以像这样：

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();
}

它的优点是在单个 SQL 语句中更新所有必需的记录。

当然，使用 EF 和 Linq 整个事情会变得更加整洁。

于 2013-02-21T18:13:20.353 回答