private void add_btn_Click(object sender, EventArgs e)
        {
            Add_Update_Assistant add_assistant_form = new Add_Update_Assistant();

            add_assistant_form.update_btn.Visible = false;
            add_assistant_form.add_btn.Visible    = true;
            add_assistant_form.heading_lb.Text    = "Add Lecturer Details";
            add_assistant_form.ShowDialog();
            this.assistant_infoTableAdapter.Fill(this.dataSet_getAssistant_Info.assistant_info);
        }
        private void assistants_info_table_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            databaseConnection.Open();
            MySqlCommand cmd1 = new MySqlCommand("Select id from assistant_info where assistant_name = '" + this.assistant_info_table.CurrentRow.Cells[0].Value.ToString() + "'", databaseConnection);
            int          id   = Convert.ToInt32(cmd1.ExecuteScalar());

            databaseConnection.Close();

            if (e.ColumnIndex == 6)
            {
                Add_Update_Assistant edit_assistant = new Add_Update_Assistant(id, this.assistant_info_table.CurrentRow.Cells[3].Value.ToString());

                edit_assistant.assistant_name_textbox.Text  = this.assistant_info_table.CurrentRow.Cells[0].Value.ToString();
                edit_assistant.work_email_textbox.Text      = this.assistant_info_table.CurrentRow.Cells[3].Value.ToString();
                edit_assistant.mobile_number_textbox.Text   = this.assistant_info_table.Rows[e.RowIndex].Cells[4].Value.ToString();
                edit_assistant.gender_combobox.SelectedItem = this.assistant_info_table.Rows[e.RowIndex].Cells[1].Value.ToString();
                string priviledge = this.assistant_info_table.Rows[e.RowIndex].Cells[2].Value.ToString();
                if (priviledge == "Assistant")
                {
                    edit_assistant.enable_checkbox.Checked = false;
                }
                else
                {
                    edit_assistant.enable_checkbox.Checked = true;
                }

                edit_assistant.update_btn.Visible = true;
                edit_assistant.add_btn.Visible    = false;
                edit_assistant.heading_lb.Text    = "Edit Assitant Details";
                edit_assistant.ShowDialog();

                this.assistant_infoTableAdapter.Fill(this.dataSet_getAssistant_Info.assistant_info);
            }
            else if (e.ColumnIndex == 7)
            {
                if (MessageBox.Show("Are you sure want to delete this record?", "Message", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                {
                    databaseConnection.Open();
                    DataGridViewRow row = assistant_info_table.Rows[e.RowIndex];
                    MySqlCommand    cmd = new MySqlCommand("Delete from assistant_info where assistant_name = '" + row.Cells[0].Value.ToString() + "'", databaseConnection);
                    cmd.ExecuteNonQuery();
                    databaseConnection.Close();
                    //remove from datatable
                    assistantinfoBindingSource.RemoveCurrent();
                    //refresh table
                    this.assistant_infoTableAdapter.Fill(this.dataSet_getAssistant_Info.assistant_info);
                }
            }
        }