Return comand...when is reader not read value

Question

1.50/5 (2 votes)

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If reader read is ok, else

{
                               notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
                               messageLabel.Text = "Radnik ne postoji u bazi! \nProverite vašu karticu ili probajte ponovo!";
                               textBox1.Text = "";
                               readerresultTextbox.Clear();

Line going to insert comand and do it...I want to return on start if reader not read
I need recommendations?

What I have tried:

private void prijavaAction()  //novija doradjena....04.04.2018
       {

           {
               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 = "";
                               readerresultTextbox.Clear();

                           }
                       }
                       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'";



                               //string queryString = "SELECT [ime_prezime] FROM dbo.radnici WHERE bar_kod = '" + textBox1.Text + "'";// pronaci radnika u bazi
                               using (SqlConnection connection1 = new SqlConnection(cs))
                               {
                                   SqlCommand command1 = new SqlCommand(queryString, connection1);
                                   connection1.Open();
                                   SqlDataReader reader1 = command1.ExecuteReader();
                                   connection.Close();
                                   try
                                   {
                                       if (reader1.Read())
                                       {


                                           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 = (reader1["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 = "";
               }
           }
       }

Posted 3-Apr-18 23:29pm

Goran Bibic

Updated 4-Apr-18 0:37am

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3 solutions

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OriginalGriff · Answer 1 · 2018-04-03T23:46:00

The INSERT is inside a finally block, which means that no matter what happens that causes an exit from the try, that code is executed.

The finally block is meant for cleaning up after an operation is completed, regardless of its success or failure - it isn't there as a form of flow control to make sure you always try and insert something!

There are two things you need to look at here:
1) Your flow control: chances are that most of the code in your finally block belongs in the body of the try, with a return being used when the reader is empty.
2) Don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

Which SQL sees as three separate commands:

SQL

SELECT * FROM MyTable WHERE StreetAddress = 'x';

A perfectly valid SELECT

SQL

DROP TABLE MyTable;

A perfectly valid "delete the table" command

SQL

--'

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

Goran Bibic · Answer 2 · 2018-04-03T23:52:00

Solution 2

Thanks for advice, some solution?

Posted 3-Apr-18 23:52pm

Goran Bibic

Comments

Richard Deeming 4-Apr-18 12:21pm

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Goran Bibic · Answer 3 · 2018-04-04T00:38:00

But readerresulttextbox late with value...if put couple wrong codes, insert into work first row with empty value from readerresulttextbox

private void prijavaAction()  //04.04. final doradjena
       {

           {
               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
                           {
                               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("#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
                               {

                                   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'";



                                   //string queryString = "SELECT [ime_prezime] FROM dbo.radnici WHERE bar_kod = '" + textBox1.Text + "'";// pronaci radnika u bazi
                                   using (SqlConnection connection1 = new SqlConnection(cs))
                                   {
                                       SqlCommand command1 = new SqlCommand(queryString, connection1);
                                       connection1.Open();
                                       SqlDataReader reader1 = command1.ExecuteReader();
                                       connection.Close();
                                       try
                                       {
                                           if (reader1.Read())
                                           {


                                               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 = (reader1["ime_prezime"].ToString()) + " je odjavljen u \n " + DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss");
                                           }
                                       }
                                       catch { }


                                   }

                               }

                           }
                           else
                           {
                               notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
                               messageLabel.Text = "Radnik ne postoji u bazi! \nProverite vašu karticu ili probajte ponovo!";
                               textBox1.Text = "";


                           }
                       }
                       finally
                       {

                       }
                   }

               }
               else
               {
                   notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
                   messageLabel.Text = "Bar kod nije važeci ili nije bar kod";
                   textBox1.Text = "";
               }



           }


       }

Return comand...when is reader not read value

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