Why dont work update ///another way

Question

private void prijavaAction()
{
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())
{
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");
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 brojprijavnice2 is NULL and radnik=" + readerresultTextbox.Text;
SqlCommand provjeraprijaveradnika = new SqlCommand(prijava);
//con.Open();
if ((prijava != null)) //radi
//if ((prijava !))
{
String saveStaff = "INSERT INTO dbo.prijava_radnika (vrijemeprijave, status, radnik) VALUES(@vrijemeprijave,'prijavljen',@radnik)";
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("@radnik", SqlDbType.VarChar, 255).Value = readerresultTextbox.Text;
openCon2.Open();
querySaveStaff.ExecuteNonQuery();
openCon2.Close();
}
}
}
else
{
String updateStaff = "UPDATE dbo.prijava_radnika SET vrijemeprijave=@vrijemeodjave, status='odjavljen' WHERE radnik=" + provjeraprijaveradnika.ToString();
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();
}
}
}
// 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 = "";
}
}