Re: URGENT: fetch previous cursor items?

From: Francis Wang <>
Date: 24 Dec 1993 19:31:19 GMT
Message-ID: <2ffg27$>

John Barton ( 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 (

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.

Francis Wang
Intertech Associates, Inc. Received on Fri Dec 24 1993 - 20:31:19 CET

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