Scalar SQL function example

The following example creates a function that compares two numbers and returns the larger value. For more information, see CREATE FUNCTION.

create function f_sql_greater (float, float)
  returns float
stable
as $$
  select case when $1 > $2 then $1
    else $2
  end
$$ language sql;  

The following query calls the new f_sql_greater function to query the SALES table and return either COMMISSION or 20 percent of PRICEPAID, whichever is greater.

select f_sql_greater(commission, pricepaid*0.20) from sales;