private void btnShCar_Click(object sender, EventArgs e) {
			com.CommandText = "getAllCars";
			Viewer child = new Viewer("Cars", com);
			this.Hide();
			child.ShowDialog();
			this.Show();
		}
		private void btnShDrv_Click(object sender, EventArgs e) {
			com.CommandText = "getAllDrives";
			Viewer child = new Viewer("Drivetrain", com);
			this.Hide();
			child.ShowDialog();
			this.Show();
		}
		private void btnShWhls_Click(object sender, EventArgs e) {
			com.CommandText = "getAllWheels";
			Viewer child = new Viewer("Tyres and wheels", com);
			this.Hide();
			child.ShowDialog();
			this.Show();
		}
		private void btnShBnC_Click(object sender, EventArgs e) {
			com.CommandText = "getAllBodies";
			Viewer child = new Viewer("Body and chassis",com);
			this.Hide();
			child.ShowDialog();
			this.Show();
		}