Efficiently retrieving only a set of records ... ?

Question

Hi,
Ours is web centric small-scale ERP. We have lot of reports which display data by pages.
While retrieving records we are using the following type of SQLs:
select col1,col2,.... from (
select rownum srno, col1, col2, ... from tables where ...)
where srno between 1 and 100;
(100 records per page)
But we know that the sub-query is going to do a full table scan and then the main query will filter the records based on the 'srno' column.
Does anybody know any better way of retrieving records without a having the sub-query do a full table scan?
I would really appreciate your response.
TIA.

Answer 1

If you are on Oracle9i, you could use the PL/SQL package DBMS_XMLQUERY to get XML output (optionally you could also
apply an XSLT stylesheet right inside the database to convert it into an HTML). This package has two procedures
setMaxRows => Maximum number of rows to return for your query
setSkipRows => Rows to skip before query results are returned
using this combination, you could call a PL/SQL package with different starting point this package will get you the
rows starting from that row (in XML format or optionally in HTML after applying XSLT).
Once you have the output, you could pass it to the front end and if needed, apply the stylesheet binding there to display
to the client.
You can also take advantage of using bind variables to query for different data values.