Search using a textbox

Hello to all! I am a newbie here in asp.net. i am making a web application. i can add reocrd on my host database but i cant make a message box if the records alrady exist. another thing i want to search a record from my host database using a textbox then display the records on a labelbox. like customerID!fileds = lblCustomer ID.text.. pls send me a complete systax for my problem.. many thanks in advance.
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