Is there an easier way to get tabular report results with select lists?

Question

Ok, as a newbie, I have gotten this query to work in my report region but I figure if I am doing something this convoluted then I am not letting a wonderful feature of HTML DB do its job.
I have 3 select lists that I want to "AND" together to filter the result list. Two of the selected items to filter could have null values.
I want to have the entire results to appear when the list is reset (clear cache is working and sets each select list value to null). However, it appears to me, if one select list is used and the others are not, the other select lists by default have %null% (Null return value setting left blank) which isn't really null.
Well if that wasn't confusing so far. Here is the select:
select [my columns]
from my_table
where (instr(upper("COL1"),upper(
decode(:P1_FILTER_COL1,'%null%',"COL1",
null,"COL1",:P1_FILTER_COL1))) > 0 -- COL1 is mandatory
AND
(instr(upper("COL2"),upper(
decode(:P1_FILTER_COL2,'%null%',"COL2",
null,"COL2",:P1_FILTER_COL2))) > 0 OR "COL2" IS NULL)
AND
(instr(upper("COL3"),upper(
decode(:P1_FILTER_COL3,'%null%',"COL3",
null,"COL3",:P1_FILTER_COL3))) = 1 OR "COL3" IS NULL)
Do I have to use decode for the select values being reset, selected/not selected? Is there some way for the Null return value setting to really be null not %null%?
Thanks,
Kelly

Answer 1

Rather than creating your report directly from a SQL statement use the "Sql Query (PL/SQL Function Body returning Sql Query)" option and re-write your code in PL/SQL. PL/SQL gives you greater control and allows you to test the "null" values and add where clauses to your SQL query based on whether or not a value was selected in the SELECT list.
For example, I have a report parameter screen that has a state drop down list that returns a value of -1 if no state is selected. I can, therefore, code:
IF :P6_STATE_CODE != -1 THEN
query := query + " WHERE state_code = ' ||
:P6_STATE_CODE ;
END IF ;
I have a more complete example if you would like to send me an email ([email protected])
Jeff