Data Reader error c#

Goran Bibic

If type value non bar code active is line 49 and no have problems multiple times...

Whene coplue times wrong bar code value I have error line 25 on code

If is bar code from database ok working fine, if is bar code not ok firs time is ok, if wronf two times bar code errorr...

Error is INVALID ATTEMP TO READ WHEN NO DATA IS PRESENT

private void prijavaAction()
{
SqlConnection con = new SqlConnection(cs);
if (textBox1.Text.All(char.IsDigit))
{
string queryString = "SELECT [ime_prezime] FROM dbo.radnici WHERE bar_kod = '" + textBox1.Text + "'";
using (SqlConnection connection = new SqlConnection(cs))
{
SqlCommand command = new SqlCommand(queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
try
{
if (reader.Read())
{
notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#2EFF36");
messageLabel.Text = (reader["ime_prezime"].ToString()) + " je prijavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
readerresultTextbox.Text = (reader["ime_prezime"].ToString());
}
else
{
notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
messageLabel.Text = "Radnik ne postoji u bazi! \nProverite vašu karticu ili probajte ponovo!";
textBox1.Text = "";
}
}
finally
{
if (reader.Read())
{
//Insert into
}
else
{
//update
}
reader.Close();
}
}
}
else
{
notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
messageLabel.Text = "Bar kod nije važeci ili nije bar kod";
textBox1.Text = "";
}
}

26 Replies

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Rafnas T P8y ago
Accepted answer
private void prijavaAction()
      {
          SqlConnection con = new SqlConnection(cs);

          if (textBox1.Text.All(char.IsDigit))

          {
              string queryString = "SELECT [ime_prezime] FROM dbo.radnici WHERE bar_kod = '" + textBox1.Text + "'";// pronaci radnika u bazi
              using (SqlConnection connection = new SqlConnection(cs))
              {
                  SqlCommand command = new SqlCommand(queryString, connection);
                  connection.Open();
                  SqlDataReader reader = command.ExecuteReader();
                  try
                  {
                      if (reader.Read())  //radi
                                          //while (reader.Read())  //radi
                      {
                          notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#2EFF36");
                          messageLabel.Text = (reader["ime_prezime"].ToString()) + " je prijavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
                          readerresultTextbox.Text = (reader["ime_prezime"].ToString());
                      }
                      else
                      {
                          notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
                          messageLabel.Text = "Radnik ne postoji u bazi! \nProverite vašu karticu ili probajte ponovo!";
                          textBox1.Text = "";

                      }
                  }
                  finally
                  {
                      string prijava = "SELECT count(*) from dbo.prijava_radnika where vrijemeprijave is not null and vrijemeodjave is null and radnik = '" + readerresultTextbox.Text + "' and redni_broj is NULL";
                      SqlCommand provjeraprijaveradnika = new SqlCommand(prijava, con);
                      con.Open();
                      int result = Convert.ToInt32(provjeraprijaveradnika.ExecuteScalar());
                      //con.Open();
                      con.Close();
                      if ((result == 0)) //radi
                                         //if ((prijava !))
                      {
                          String saveStaff = "INSERT INTO dbo.prijava_radnika (vrijemeprijave, status, radnik,idfakture) VALUES(@vrijemeprijave,'prijavljen', '" + readerresultTextbox.Text + "',@idfakture)";
                          using (SqlConnection openCon2 = new SqlConnection(cs))
                          {
                              using (SqlCommand querySaveStaff = new SqlCommand(saveStaff))
                              {
                                  querySaveStaff.Connection = openCon2;
                                  querySaveStaff.Parameters.Add("@vrijemeprijave", SqlDbType.DateTime).Value = DateTime.Now;
                                  querySaveStaff.Parameters.Add("@idfakture", SqlDbType.Int).Value = id_fakture;
                                  openCon2.Open();
                                  querySaveStaff.ExecuteNonQuery();
                                  openCon2.Close();

                                  //notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FFE11A");
                                  // messageLabel.Text = (reader["ime_prezime"].ToString()) + " je prijavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
                              }
                          }
                      }
                      else
                      {

                          String updateStaff = " declare @maxNo integer = 0 select @maxNo = isnull(max(redni_broj), 0) from[dbo].[prijava_radnika] UPDATE[dbo].[prijava_radnika] SET"
                              + " [vrijemeodjave] = @vrijemeodjave,[redni_broj] = (@maxNo+1),[status] = 'odjavljen' WHERE radnik = '" + readerresultTextbox.Text + "'and[status] = 'prijavljen'";


                          using (SqlConnection openCon3 = new SqlConnection(cs))
                          {
                              using (SqlCommand queryupdateStaff = new SqlCommand(updateStaff))
                              {
                                  queryupdateStaff.Connection = openCon3;
                                  queryupdateStaff.Parameters.Add("@vrijemeodjave", SqlDbType.DateTime).Value = DateTime.Now;
                                  openCon3.Open();
                                  queryupdateStaff.ExecuteNonQuery();
                                  openCon3.Close();

                              }
                          }

                          string queryString = "SELECT [ime_prezime] FROM dbo.radnici WHERE bar_kod = '" + textBox1.Text + "'";// pronaci radnika u bazi
                          using (SqlConnection connection = new SqlConnection(cs))
                          {
                              SqlCommand command = new SqlCommand(queryString, connection);
                              connection.Open();
                              SqlDataReader reader = command.ExecuteReader();
                              try
                              {
                                  if (reader.Read())
                                  {
                                      notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FFE11A");
                                      messageLabel.Text = (reader["ime_prezime"].ToString()) + " je odjavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
                                  }
                              }
                              catch { }
                          }
                          // Always call Close when done reading.
                          reader.Close();
                      }
                  }
              }
          }
          else
          {
              notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
              messageLabel.Text = "Bar kod nije važeci ili nije bar kod";
              textBox1.Text = "";
          }
      }
Goran Bibic8y ago
On your code line 25,26 after tha app must do nothing...but app insert empty row
Goran Bibic8y ago
Error is on Line 25, 26,27....is problem....when put digits...app work insert comand last resulttextbox or empty row

if I put some letters going to line 103 and do nothing...thast working fine.
Goran Bibic8y ago
When put wrong code or just hit enter hi insert into empty row or last resulttextbox...I want when is error or wrong code...do nothing..
Rafnas T P8y ago
what is the problem now
Rafnas T P8y ago
line no 66 to 77 that is the below code cut that
using (SqlConnection openCon3 = new SqlConnection(cs))
                         {
                             using (SqlCommand queryupdateStaff = new SqlCommand(updateStaff))
                             {
                                 queryupdateStaff.Connection = openCon3;
                                 queryupdateStaff.Parameters.Add("@vrijemeodjave", SqlDbType.DateTime).Value = DateTime.Now;
                                 openCon3.Open();
                                 queryupdateStaff.ExecuteNonQuery();
                                 openCon3.Close();

                             }
                         }
and past it into inside if(reader1.read()) that is after line 88
Goran Bibic8y ago
Solved NOW. Thank you
Goran Bibic8y ago
Error is:

When put insert into sql work fine, deliberately put couple wrong codes...and try right code app must then work update...butt app automaticly work update when I put wrong code.

I want when reader read to do insert or update...when is worng code to do nothing...some litle mistake
Goran Bibic8y ago
Working fine. Have some simple error...

When I put some right code, app working
if ((result == 0)) //radi

{
String saveStaff = "INSERT INTO dbo.prijava_radnika (vrijemeprijave, status, radnik,idfakture) VALUES(@vrijemeprijave,'prijavljen', '" + readerresultTextbox.Text + "',@idfakture)";
That is ok...
else work update fine...errorr is on next reply
String updateStaff = " declare @maxNo integer = 0 select @maxNo = isnull(max(redni_broj), 0) from[dbo].[prijava_radnika] UPDATE[dbo].[prijava_radnika] SET"
+ " [vrijemeodjave] = @vrijemeodjave,[redni_broj] = (@maxNo+1),[status] = 'odjavljen' WHERE radnik = '" + readerresultTextbox.Text + "'and[status] = 'prijavljen'";
Rafnas T P8y ago
remove line no 79,80,81,82,83,84,85,86,87,89,90,91,92,93,and 94

and write below code

or just rename red one as below
using (SqlConnection connection1 = new SqlConnection(cs))
{
    SqlCommand command1 = new SqlCommand(queryString, connection1);
nection1.Open();
    SqlDataReader reader1 = command1.ExecuteReader();
    try
    {
        if (reader1.Read())
        {
            notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FFE11A");
             messageLabel.Text = (reader1["ime_prezime"].ToString()) + " je odjavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
        }
    }
    catch { }
}
Rafnas T P8y ago
remove line no 79 to 94

and write below code there
if (reader.Read())
{
  notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FFE11A");
  messageLabel.Text = (reader["ime_prezime"].ToString()) + " je odjavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
}
Goran Bibic8y ago
Its alredy defined in line 8,9,10,11...look in code
Goran Bibic8y ago
Parameters in line 79,80,82,84 alredy defined
Rafnas T P8y ago
from line 76, I have changed some code pls try this, the problem is there also you have to check
if(reader.Read())
Goran Bibic8y ago
Your recommendations?
Rafnas T P8y ago
in line 77 there is no reader like in line 16, you have to write same in line 77 also
Goran Bibic8y ago
Invalid attempt to read when no data is present.

That is errorr...line 16 update code
String updateStaff = " declare @maxNo integer = 0 select @maxNo = isnull(max(redni_broj), 0) from[dbo].[prijava_radnika] UPDATE[dbo].[prijava_radnika] SET"
                               +" [vrijemeodjave] = @vrijemeodjave,[redni_broj] = (@maxNo+1),[status] = 'odjavljen' WHERE radnik = '" + readerresultTextbox.Text + "'and[status] = 'prijavljen'";


                           using (SqlConnection openCon3 = new SqlConnection(cs))
                           {
                               using (SqlCommand queryupdateStaff = new SqlCommand(updateStaff))
                               {
                                   queryupdateStaff.Connection = openCon3;
                                   queryupdateStaff.Parameters.Add("@vrijemeodjave", SqlDbType.DateTime).Value = DateTime.Now;
                                   openCon3.Open();
                                   queryupdateStaff.ExecuteNonQuery();
                                   openCon3.Close();

                                   notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FFE11A");
                                   messageLabel.Text = (reader["ime_prezime"].ToString()) + " je odjavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
                               }
                           }
                       }
Rafnas T P8y ago
what isthe error you are getting
Goran Bibic8y ago
hi,
you have to remove line 19 to line 24 full of else bolck (else{} 19,20,21,22,23,24 remove)

Removeed...first time ok...another time same error
Rafnas T P8y ago
hi,
you have to remove line 19 to line 24 full of else bolck (else{} 19,20,21,22,23,24 remove)
Goran Bibic8y ago
Remove else block (lines 18,19 and 20).

Now no have no one worker ...every time is text from line 22....Like no have users in table...and after two times wrong code same error
Rafnas T P8y ago
When you use while you have to remove else block
Goran Bibic8y ago
Insert while instead if on line 13 and I have error line 18...expeted }
Goran Bibic8y ago
I try for 10 minutes
Rafnas T P8y ago
if you wanted to fetch more data rows then use

while (reader.Read())

instead of

if (reader.Read())
Rafnas T P8y ago
hi,
try below link

https://stackoverflow.com/questions/1147615/invalid-attempt-to-read-when-no-data-is-present?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa