How to Efficiently Convert ResultSet to Paginated View on JSP?

Converting ResultSet to a Paginated View on JSP

To effectively convert a ResultSet object into a paginated view on a JSP, it's essential to introduce additional request parameters: firstrow and rowcount. The first parameter defines the starting record for pagination, while the second (optional) parameter specifies the number of records to display on a single page.

Creating Pagination Buttons

Next, the JSP should include pagination buttons that facilitate navigation through the results. The "next" button increments the firstrow value by the rowcount, and the "previous" button decrements it accordingly. It's important to handle negative values and overflows correctly by setting appropriate boundaries.

Using Specific SQL Queries to Retrieve a Sublist

To retrieve a specific subset of results, it's necessary to fire a modified SQL query. The exact syntax for this query depends on the database being used.

MySQL and PostgreSQL:

<code class="sql">SELECT id, username, job, place FROM contact ORDER BY id LIMIT %d OFFSET %d;</code>

Oracle:

<code class="sql">SELECT id, username, job, place FROM (SELECT id, username, job, place FROM contact ORDER BY id) WHERE ROWNUM BETWEEN %d AND %d;</code>

DB2:

<code class="sql">SELECT id, username, job, place FROM (SELECT row_number() OVER (ORDER BY id) AS row, id, username, job, place FROM contact) AS temp WHERE row BETWEEN %d AND %d;</code>

CSS/JavaScript and JSP

The sublist is then presented in the JSP using JSTL's c:forEach. Finally, a form is provided to handle the pagination functionality.

Avoiding Memory Inefficiency

It's important to note that selectively retrieving data for pagination avoids the inefficient approach of storing the entire table results in the session scope and using List#subList(). This method ensures memory efficiency, especially in scenarios with large datasets and concurrent users.

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