how make one query item has two filter?

[silywiwi]

   hi all! me too:)
   i want to give a query item  two filter
   the query item accept the parameter by prompt page
   the name of query item is 'studentName',
   when the length of parameter greater than 9, i will use "studentName = ?para?"
   else i will use "studentName contains ?para?"
  how can i  make the requirement come true?
  thanks in advance!!

[almeids]

Use filter:
(length(param)>9 and (studentname=param)) or (length(param<=9) and (studentname contains param))