Can I create a custom function in SQL ?

Question

Here, SUM(),AVG(),SQRT() are pre-defined function. So can I create a new function ?

Answer 1

CREATE FUNCTION  function-name (Parameters)  

RETURNS  return-type  

AS  

BEGIN  

    Statement 1  

    Statement 2  

             .  

             .  

    Statement n  

    RETURN return-value  

END

Yes! you can, This is the way of creating function

Answer 2

"Select cust(column2) as custom from student;"

Here how to define cust function in query box?