This code looks similar to what I used. However, I'll make one point about
making it a bit quicker (at least in the earlier pages).
The code basically returns the entire resultset, and loops through it, adding
rows for the page in question to a vector while ignoring the rows before and
after those of interest. Okay. ORACLE provides a pseudo column called
ROWNUM which is similar to, yet different from the LIMIT of other DBs like
PostgresQL. SQL to the effect of
"SELECT <whatever> FROM <whatever> WHERE <whatever> AND ROWNUM BETWEEN 100 and
120"
****will not work****. It will always return 0 rows. However it will work if
you put only the upper limit on it. EG:
"SELECT <whatever> FROM <whatever> WHERE <whatever> AND ROWNUM <= 120"
will work fine.
In other words, you need to loop and skip all rows before the disired rows,
but you don't need to return nor loop through skipping the ones following.
Similarily, you could change the while loop from:
-- <snip> ---
> while (rs.next()) {
> nNumRows++;
>
> if ( (nNumRows >= p_nStartRow) && (nNumRows <
> p_nStartRow + p_nMaxRows) ) {
> // Populate our transaction list objects
> TransactionList transactionlist = new
> TransactionList(rs.getString(3), rs.getString(5),
> rs.getInt(6), rs.getString(7),
> rs.getString(8),
> rs.getBigDecimal(9, 2), rs.getBigDecimal(10, 2),
> rs.getBigDecimal(11, 2), rs.getBigDecimal(12, 4),
> rs.getBigDecimal(13, 4), rs.getBigDecimal(14, 4),
> rs.getString(15), rs.getString(17),
> rs.getString(22),
> rs.getLong(1), rs.getString(19),
> rs.getString(23), rs.getString(24),
> rs.getString(25));
> vData.addElement(transactionlist);
> }
> }
--- <end snip> ----
To:
_-- <snip> ---
> while (rs.next() && (nNumRows < p_nStartRow + p_nMaxRows)) {
--- cut (rest of the loop is the same) -----
to do the same thing without the pseudo column.
Someone else had reply about a scrollable resultset which might be more
effiecient than this solution, but I have no experience with that.
Hope this helps,
Don Brown
On November 21, 2002 11:56 am, [EMAIL PROTECTED] wrote:
> Ok guys I'm giving you all a gift.... I had the same problem understanding
> how PetStore does it and after reading much documentation on the design
> pattern and various other people's implementation of said pattern here is
> my interpretation of the Page-by-Page Iterator pattern...
>
> This is actually still being used in production for a project developed
> from three years ago so I know it works... Don't give me a hard time about
> using a Vector though... If you want to use an ArrayList instead by all
> means feel free to change it!
>
> Debug is a class I wrote for outputting values while developing/unit
> testing so implement your own such as Log4J or whatever. I'ved also removed
> the bulk of the SQL statement as it is somewhat proprietary but I think you
> will get the drift...
> --- <Code is in original reply from [EMAIL PROTECTED]> ---
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