prevent duplicate records

my project has a customer table with id and name.
I need to prevent Someone from putting a customer in twice. the code below is not work ay because I do it know how to get the name value I just put in.
the way it should work is if Charlie Brown is in the database and they try to put him the again it will say "Charlie Brown is already in the system"
if it was really Cool it would show near matches too just in case they misspell -"Charles Brown is already in the system"
// Parameters:

// $values - Array object.

// Each field on the Add form is represented as a 'Field name'-'Field value' pair
//** Check if specific record exists ****

global $conn;

$strSQLExists = "select * from tbl_customers where name='name-$value'";

$rsExists = db_query($strSQLExists,$conn);

$data=db_fetch_array($rsExists);

if($data)

{

// if record exists do something

}

else

{

// if dont exist do something else

}
return true;
// return true if you like to proceed with adding new record

// return false otherwise