Re: URGENT: fetch previous cursor items?

John Barton (jbarton_at_empros.com) wrote:

: Is there a method for fetching the previous items in a cursor?
 

: I'm trying to use a scrolling list and only store the visible items in memory
: at any one time. (i.e. I want to get the next 'n' items when the user
: scrolls down, and the previous 'n' items when they scroll up)
 

: John Barton (jbarton_at_empros.com)

If your query can be ordered by an unique index then you can use the following technique:

• Display rows in the order of the unique index.
• When you're going forward store the index key (in memory) of the rows you retrieved.
• When you need to scroll up, close the current cursor and open a new cursor that has the query defined as'order by key desc' with a where clause : 'where key < last_index_value'.

  I would recommand buffer more rows than just a screen full. This   technique is used by some vendors to implement scrolling.