manoj kumar wrote:
> Hi Andras/Pradeep,
>
> Thanks for the help.
> My problem is a little bit more complicated.
> I am able to pass values from a HTML element to a Servlet.
> My problem is that based on that value I want to fire a query on a table.
> Let me further expalin the problem.
> Upon clicking a HTML link(or button), a servlet is called(A), which fires a
> select query on a table
>
> select category_description from category_master
>
> The result of this query is formatted into an html page and sent back
> to browser.Now the user selects a particular category and presses
> submit/next(whatever).This results in a call to another servlet(B) or
> the same servlet(A,how..?) which in turn fires another query
>
You don't need JavaScript to do this, although you could use it for some
fancier user interface effects.
The simplest approach:
* Change the above query to something that selects the
key as well as the description:
select category_code, category_description
from category_master
* In servlet A (the one that does the query above), create
an HTML table with one row per category. The table will
show the descriptions in a column.
* For each category description, create a hyperlink to your
second servlet, passing the category code as a query
parameter. You'll end up with something like this:
<tr><td>
<a href="/servletB?category=xxxxx">yyyyy</a>
</td></tr>
where "/servletB" is the URL of your second servlet,
xxxxx is the category code for this row, and yyyyy is
the category description for this row.
* The user sees a list of hyperlinks. When he or she clicks
one, it calls servlet B and passes the category code of the
selected category. In servlet B, you can retrieve this with:
String category = request.getParameter("category");
* Use this to dynamically construct your second SQL statement.
>
> select product_name from product_master where category_code=xxxxxx
> This 'xxxxxxx' is something which should correspond to the category selected
> by the user in the previously generated html page(by servlet A).
> I was thinking of making it possible through javascript but couldn't find a
> solution.
>
You could use a similar approach to the above to create, for example, a
<select> element for the categories instead of a list. If you add an
"onchange" JavaScript event handler, you could even have it submit the request
immediately, without waiting for another button to be pressed. See one of the
many web sites focused on JavaScript for details of how to do this.
>
> hope this clears the idea.
>
> help is immidiately needed.
>
> thanks
>
> manoj
>
Craig McClanahan
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