Passing month to pl/sql function?

Question

I want to Write a function that returns the Products brought in a given month.

I tried this

 create or replace 
 function myfun(mymonth date) 
    return date
 is  
    cursor cur 
    is 
       select * 
         from products 
        where purchase_date=mymonth;
 begin
    for i in cur
    loop
       dbms_output.put_line(i.product_id || ', ' || 
                            i.description || ', ' || 
                            i.product_name || ', ' || 
                            i.quantity || ', ' || 
                            i.price || ', ' || 
                            i.purchase_date);
    end loop;
    return 1;
 end;  

this giving me error. how can i pass month to pl/sql function and retrieve the data.

Answer 1

Pass in a date ('01-MAY-2003') and use date functions to make it work:

create or replace 
 function myfun(mymonth date) 
    return date
 is  
    cursor cur 
    is 
       select * 
         from products 
        where purchase_date >= TRUNC(mymonth, 'MM')
          and purchase_date < ADD_MONTHS( TRUNC(mymonth,'MM') , 1 );

Using TRUNC(x, 'MM') on the input month means you can pass in any date at teh query will run from the first day of the month.

Alternatively, you could use the LAST_DAY() function which returns the start of the last day of the input month. You'd have to watch out for time values, since the Oracle DATE datatype can include both date and time.

Answer 2

I think that what you need is only to compare the month from the purchase_date column with the month on the param of the function...

I would do it this way

cursor cur 
is 
   select * 
     from products 
    where TO_CHAR(purchase_date,'MM') >= TO_CHAR(mymonth, 'MM')

If you want to include also the year, you could use 'RRRRMM' as a param of TO_CHAR, instead of 'MM'