Error building table

Question

Can someone please guide me in the right direction? I'm trying to build a table based on certain calculations. However once I add my pdate date variable and the appropriate calculation I get the following error:
ORA-01858: a non-numeric character was found where a numeric was expected
I've tried every way I can to try and solve this. Is this possible or can I not manipulate the data using PL/SQL in this manner?
The PL/SQL query so far is:
declare
per varchar2(6):= '0.0';
pdate date := 'TRUNC (TO_DATE (:P4_START_DATE, ''MM/DD/YYYY'') - TRUNC (TO_DATE (:P4_END_DATE, ''MM/DD/YYYY'')))
FROM dual';
begin
htp.p('<table BORDER="1" CELLSPACING="0" CELLPADDING="0" WIDTH="100%">');
htp.p('<tr BGCOLOR="#FF0000">');
htp.p('<th>DAY</th>');
htp.p('</tr>');
htp.p('<tr BGCOLOR="#FF0000">');
htp.p('<th>PERCENT</th>');
for i in 1..48 loop
htp.p('<th>' ||per||'</th>');
end loop;
htp.p('</tr>');
htp.p('<tr BGCOLOR="#FF0000">');
htp.p('<th>PEOPLE</th>');
htp.p('</tr>');
end;
Erin

Answer 1

Doug,
I thought it would be best if you saw a visual of how my report looks now and how I want to build a table in order to change the look of the report.
If created a login of guest01 with a password of today01 at:
http://apex.oracle.com/pls/otn/f?p=21615:4:1348767953274673:::::
If you enter any set of dates and select any application or applications you shoudl see the output.
If you look at my "Availability" region, this is the region where I've created my SQL query and everything works perfectly with the exception of the formatted output. I need the output to imitate that of the "Test" region. I need the days to loops through the first row then the percentages and then the application.
I only want 1 row per application instead of the application and percentages listed in a separate row for every day selected.
Hopefully this helps gives a visual and if there are any suggestions on how I can get this to work I can truly use the help. Thanks
Erin