There is already an open datareader associated with this command which must be closed first.

Question

1.00/5 (1 vote)

See more:

C#

string connectionstring = "Server=(local);initial catalog=Test;Trusted_Connection=True";
               SqlConnection sqlConnection = new SqlConnection(connectionstring);
               SqlCommand cmd = new SqlCommand();
               SqlDataReader reader,reader1;
               DataSet ds = new DataSet();
               cmd.CommandText = "select * from Empdetails";
               cmd.CommandType = CommandType.Text;
               cmd.Connection = sqlConnection;
               sqlConnection.Open();
               reader = cmd.ExecuteReader();
               reader1 = cmd.ExecuteReader();
               if (reader.HasRows)
               {
                   System.IO.StreamWriter sw_In = new System.IO.StreamWriter(@"C:\Users\God\Desktop\DataDump\IN_Excel.xls");
                   if (reader.Read())
                   {
                       string status = reader[6].ToString();
                       if (status == "1") ;
                       {
                           for (int i = 0; i < reader.FieldCount; i++)
                           {
                               sw_In.AutoFlush = true;
                               sw_In.Write(reader[i].ToString() + "\t");
                           }
                           sw_In.Write("\n");
                       }
                   }
                   reader.Close();
               }

                   if (reader1.HasRows)
                    {
                           System.IO.StreamWriter sw_Out = new System.IO.StreamWriter(@"C:\Users\God\Desktop\DataDump\OUT_Excel.xls");
                      if (reader1.Read())
                       {
                       string status1 = reader1[6].ToString();
                      if(status1 == "2");
                         {
                           for (int i = 0; i < reader1.FieldCount; i++)
                           {
                               sw_Out.AutoFlush = true;
                               sw_Out.Write(reader1[i].ToString() + "\t");
                           }
                              sw_Out.Write("\n");
                        }

                      }
                      reader1.Close();
                  }
               sqlConnection.Close();

When i run the above code shows error as follows

There is already an open DataReader associated with this Command which must be closed first.

i already close DataReader

for that DataReader close code as follows

reader.Close();

Whehter i close the Datareader line is correct or need to mention that Reader close in other line of my code.

What I have tried:

There is already an open DataReader associated with this Command which must be closed first.

Posted 15-Aug-16 2:58am

sudhakarthikeyan

Updated 15-Aug-16 3:18am

Patrice T

v2

Add a Solution

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

F-ES Sitecore · Answer 1 · 2016-08-15T03:05:00

Solution 1

You have two readers for the same command

C#

reader = cmd.ExecuteReader();
reader1 = cmd.ExecuteReader();

Readers are only for data that you want to go through once. As you need to go through the data twice use a DataSet instead.

Posted 15-Aug-16 3:05am

F-ES Sitecore

Nathan Minier · Answer 2 · 2016-08-15T03:10:00

So, your problem is:

C#

reader = cmd.ExecuteReader();
reader1 = cmd.ExecuteReader();

The exception tells you that this is a problem. There is no reason to do this.

Also, you're leaving a whole bunch of undisposed handles floating around when you do this. The rule of thumb is: If something implements IDisposable, dispose of it when you're done with it.

C#

using(var reader = cmd.ExecuteReader())
{
...
}

Patrice T · Answer 3 · 2016-08-15T03:18:00

Solution 3

Quote:
i already close DataReader

You don't understand that reader1 is opened at

C#

reader1 = cmd.ExecuteReader();

which is before you close reader.

Rule of thumb: the error message exist for reason, it imply that you are wrong, just have to find why.

Posted 15-Aug-16 3:18am