REP 300 error when using dynamic where clause

Question

Hi,
I am developing a report and I need a dynamic where clause.The code I have written in the where clause is as below
function where_clauseFormula return VARCHAR2 is
begin
if :P_PO_REQD = 'No' then
return ('and pha.segment1 is null');
elsif :P_PO_REQD = 'Yes' then
     return('and pha.segment1 between NVL(:p_po_num_from,1) and NVL(:p_po_num_to,99999999999999999)');
else return NULL;
end if;
end;
Now if i directly use either of the conditions in my report query it works fine.But if the parameter is No then the where clause does not work.I have also tried different statements in the if clause of the 'No' part and they work.For example the following code works when :P_PO_REQD is 'No' :
function where_clauseFormula return VARCHAR2 is
begin
if :P_PO_REQD = 'No' then
return ('and pha.segment1 between NVL(:p_po_num_from,1) and NVL(:p_po_num_to,99999999999999999)');
elsif :P_PO_REQD = 'Yes' then
     return('and pha.segment1 between NVL(:p_po_num_from,1) and NVL(:p_po_num_to,99999999999999999)');
else return NULL;
end if;
end;
I don't know why this is happening.I really need a solution or a workaround urgently
Thanks
Mukund

Answer 1

You may use Lexical Reference for the dynamic where. In After Parameter Form Trigger, code....
if :P_PO_REQD = 'No' then
:P_where := :P_where || 'and pha.segment1 is null';
elsif :P_PO_REQD = 'Yes' then
:P_where := :P_where || 'and pha.segment1 between NVL(:p_po_num_from,1) and NVL(:p_po_num_to,99999999999999999)';
end if;
..........