private void addStudentsToolStripMenuItem_Click(object sender, EventArgs e)
{
Add_Students addstd = new Add_Students();
addstd.MdiParent = this;
addstd.Show();
addstd.Activate();
}
private void button1_Click(object sender, EventArgs e)
{
int res = bl.Add_Student(textBox1.Text, textBox2.Text, textBox3.Text, textBox4.Text, textBox5.Text, dateTimePicker1.Text, textBox7.Text, textBox6.Text, richTextBox1.Text);
MessageBox.Show("Student Details Registered Success");
Add_Students add = new Add_Students();
add.Show();
this.Hide();
}