SQL & PL/SQL

Greetings -

I have a block of code on a report in grid control and it works ok.
What annoys me is that I need to specify the parameter in the
open cursor so many times. I know there is an easier way.
Here is a simple example of that section:


dt1 := sysdate - 90

my_str := 'select * from my_table where collection_timestamp
between :1 and (:1 + 1)';

open cursor my_cursor for my_str using dt1, dt1;

However - in my code I use this about 24 times. Any help would be appreciated.

Thanks,

Brian