ADO.Net DataReader错误：已经是Open DataReader

I am using C# + .Net 3.5 + VSTS 2008 + ADO.Net + SQL Server 2008. And I am sharing one single SQL Connection object (TestDBConnection variable in my below sample) within my application.

我正在使用C#+ .Net 3.5 + VSTS 2008 + ADO.Net + SQL Server 2008.我正在我的应用程序*享一个单独的SQL连接对象(我的下面示例中的TestDBConnection变量)。

The exception I met with is, "There is already an open DataReader associated with this Command which must be closed first.." Any ideas what is wrong?

我遇到的例外情况是,“已经有一个与此命令关联的开放DataReader必须首先关闭..”任何想法有什么问题?

The patterns within my application which I am using are all like this, i.e. sharing the single db connection object TestDBConnection, and using the single TestDBConnection variable to create command on it and execute store procedure.

我正在使用的应用程序中的模式都是这样的,即共享单个数据库连接对象TestDBConnection,并使用单个TestDBConnection变量在其上创建命令并执行存储过程。

        using (SqlCommand testCommand = new SqlCommand())
        {
            testCommand.Connection = TestDBConnection;
            testCommand.CommandType = CommandType.StoredProcedure;
            testCommand.CommandText = "prc_AddOrderStatus";
            testCommand.Parameters.Add("@orderID", SqlDbType.NVarChar).Value = orderID;
            testCommand.ExecuteNonQuery();
        }

thanks in advance, George

乔治,提前谢谢

3 个解决方案

#1

Don't share the connection, use connection pooling instead. If you are doing two things at the same time on the connection, you might want to look into MARS.

不要共享连接,而是使用连接池。如果您在连接上同时执行两项操作,则可能需要查看MARS。

For a test add this to your connection string: ;MultipleActiveResultSets=True; and see if this "fixes" the error. A lot of people believe you should avoid using MARS, so this is something to consider.

对于测试,将此添加到您的连接字符串:; MultipleActiveResultSets = True;并查看这是否“修复”了错误。很多人认为你应该避免使用MARS,所以这是需要考虑的事情。

#2

using (sqlConnection theconnection = new sqlconnection(initialise it))
{
 using (SqlCommand testCommand = new SqlCommand())
        {
            testCommand.Connection = theConnection
            testCommand.CommandType = CommandType.StoredProcedure;
            testCommand.CommandText = "prc_AddOrderStatus";
            testCommand.Parameters.Add("@orderID", SqlDbType.NVarChar).Value = orderID;
            testCommand.ExecuteNonQuery();
        }
}

is the pattern that i use in multi threaded cases with no problems at all.

是我在多线程案例中使用的模式,完全没有问题。

Incidently this is connection pooling.

这是连接池。

#3

George, is it possible that the exception is telling you the truth? Are there any other commands that you've started but not yet finished?

乔治,这个例外有可能告诉你真相吗?是否还有其他命令已经启动但尚未完成?

#1