如何在任何条件下将列的值提取到列表框？

I have a database and there is an 'users table' in it. In this table, there are columns which contain users information (site, nick, jeton, mail, sifre). I am trying to make a program based on a credit system. Any user runs the program, than, if the users credit is equal to number of sites in listbox (i mean number of lines) the users site will appear in the listbox. Otherwise, it won't appear.'