how to automatic data retrieve from the database

Dear All, i m using vs2008 and sql database. I have a autocomplete text box and I want to retrieve value from the database . For ex. I have a text box named “customerName” second textbox named “address” third textbox “balance”. Now I want, when I typed in the customerName then it will show automatically his address and balance value from the database. pls give me a example code.