private void studEst_FormClosing(object sender, FormClosingEventArgs e)
 {
     studentWork sw = new studentWork(numStud);
     sw.Show();
     this.Hide();
 }
 private void checkStudent()
 {
     conn = new SqlConnection(connectionString);
     conn.Open();
     SqlCommand comm = new SqlCommand();
     comm.Connection = conn;
     comm.CommandText = "select [№ студента] from Студент where Фамилия = '"+ textBox1.Text +"' and Имя = '"+ textBox2.Text +"' and Отчество = '"+ textBox3.Text +"' and Пароль = '"+ textBox4.Text +"'";
     SqlDataReader rdr = comm.ExecuteReader();
     if (rdr.HasRows)
     {
         label6.Visible = false;
         rdr.Read();
         studentWork sw = new studentWork(rdr[0].ToString(),textBox4.Text);
         sw.Show();
         this.Hide();
     }
     else
     {
         label6.Visible = true;
         clearColumns();
     }
     rdr.Close();
     conn.Close();
 }
 private void выходToolStripMenuItem_Click(object sender, EventArgs e)
 {
     if (MessageBox.Show("Вы уверены, что хотите вернуться в систему?", "Подтверждение", MessageBoxButtons.OKCancel) == DialogResult.OK)
     {
         string pass = (string)SelectPassStud();
         studentWork studwork = new studentWork(NumStud.ToString(), pass);
         this.Hide();
         studwork.Show();
     }
 }