retrieve information from database

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hello

I need to retrieve information from database
what the code I should use

C#

string ip;
                        ip = GetIP();
                        SqlCommand command = new SqlCommand("SELECT DeviceName FROM ConnectedDevice  WHERE IP= @IP AND IDName=@IDName  ", connection);
                        command.Parameters.Add(new SqlParameter("@IP", ip));
                        command.Parameters.Add(new SqlParameter("@IDName", name));
                        command.ExecuteNonQuery();

                        SqlDataReader reader1 = command.ExecuteReader();
                         if (reader1.HasRows)
                            {

                                device = reader1.GetValue(0).ToString();
                                
                              
                            }

the code

C#

device = reader1.GetValue(0).ToString();

do not retrieve any thing and give an error
what the code should I replace it with ??

thanks :)

Posted 23-May-12 22:55pm

maxpower12345

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Maciej Los · Accepted Answer · 2012-05-23T23:03:00

Solution 1

Take a look here: SqlDataReader Class[^] - on the bottom of page you'll find a solution: how to read data from datareader?

Posted 23-May-12 23:03pm

Maciej Los

Updated 23-May-12 23:04pm

v2

Comments

maxpower12345 24-May-12 5:14am

thanks

but still give an error :(

"invalid attempt to read when no data is present "

while the is data in database

maxpower12345 24-May-12 5:20am

thanks its work :)

Sandeep Mewara 24-May-12 5:37am

Good answer. 5!

Maciej Los 24-May-12 5:53am

Thank you, Sandeep ;)

John Orendt · Accepted Answer · 2012-05-23T23:05:00

Solution 2

To start for a select statement, replace

C#

command.ExecuteNonQuery();

with

C#

SqlDataAdapter sqlDa = new SqlDataAdapter(command);
DataSet ds= new DataSet();
sqlDa.Fill(ds);

Posted 23-May-12 23:05pm

John Orendt

bhagirathimfs · Accepted Answer · 2012-05-23T23:06:00

Solution 3

Instate of this

C#

if (reader1.HasRows)
{
       device = reader1.GetValue(0).ToString();
}

Write this

C#

if (reader1.HasRows)
{
   if(reader1.Read())
   {
       device = reader1.GetValue(0).ToString();
   }
}

and you can remove this line(delete this line)

C#

command.ExecuteNonQuery();

Posted 23-May-12 23:06pm

bhagirathimfs

Updated 23-May-12 23:09pm

v2

akee seth · Accepted Answer · 2012-05-23T23:18:00

Solution 4

You can use like this also

C#

 if (reader1.HasRows)
{
 while(reader1.Read())
  {
     device = reader1["your column name"].ToString();
  }
}

Posted 23-May-12 23:18pm

akee seth