c# - How to change Textbox text with each scanned barcode and fire ontextchange event -

i trying change text inside textbox everytime barcode scanned. program able take scanned barcode , fetch data database based on barcode text using ontextchange event, when scanned barcode on second time added barcode next first barcode input. example :

1. 00111104
2. 0011110400111105

i facing 2 error in here:

first, barcode scanned added next first one.

second, ontextchange event can't fire without taking focus outside textbox. using asp.net using vb code behind. here code far:

private sub selectdata()          sql = "select * tbl_take [badge id] = '" + txtscanid.text + "'"     cmd = new sqlcommand(sql, con)      drdatareader = cmd.executereader     while (drdatareader.read())         'taking data database'         end while  end sub  protected sub txtscanid_textchanged(sender object, e eventargs) handles txtscanid.textchanged     call selecteddata() end sub 

i set focus on txtscanid inside page load.

can me how make current barcode scanned replace last barcode in textbox. there other way fire ontextchange?

thanks in advances. appreciate though.