private void comboBox3_SelectedIndexChanged(object sender, EventArgs e) { if (comboBox3.ValueMember == "ID") { DataTable dt = bllss4.getBatchRequired(int.Parse(comboBox3.SelectedValue.ToString())); batch = bool.Parse(dt.Rows[0][0].ToString()); if (batch == true) { textBox1.Text = "True"; textBox1.Enabled = true; } else { textBox1.Text = ""; textBox1.Enabled = false; } } }