Re: Best way to do this?

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 22 Jul 2010 18:10:14 +0100

Message-ID:

<alpine.DEB.1.10.1007221801370.13293@urchin.earth.li>

On Thu, 22 Jul 2010, harryajh wrote:

I have to process a large number of database records, examine a column
value (can be 10 different values) and set a bean's property depending
on that fields values e.g (vastly cut down)

ResultSet rs = ps.executeQuery();
while (true)
    {
        ret = new myBean();
        String propName = rs.getString(2);
        if (propName.equalsIgnoreCase("licence_number"))
        {
          ret.setLicenceNo(rs.getString(3));
        }
        else if (propName.equalsIgnoreCase("return_requirement_id"))
        {
          ret.setReturnReqId(rs.getString(3));
        }
    }

Hopefully its relativily easy to follow what I'm trying to do, my big
problem though is using a "String" to hold the fields value, this
obviously is not a good idea and surely for performance reasons
neither would -

if (rs.getString(2).equalsIgnoreCase("licence_number"))

or wouldn't it make much difference getting the field value up to 10
times?

Compared to the cost of going to the database, no, not at all.

An alternative approach would be to change your query to include "and
prop_name = 'license_number'", then you know that everything that comes
back is a license number, and so don't have to check. Then do the same
again for the other beans. However, that would rather increase the number
of queries you make, which is not likely to aid performance!

You could also do an N-way self-outer-join, which would put the values
stored against each property name in different columns in the result set.
I think the SQL for that would be a bit fiendish, though.

tom

--
got a DOCTORATE in cold ROCKIN' IT