Query of a Query and Query Cache

[Bygbobbo]

Has anyone ever used Query of a Query in Java? Similar to how Cold Fusion lets you use record sets.

I am also trying to cache a query and set how long I want it to stay cached in the database.

I am using MS SQL 2000..

Thanks in advance,
Bygs

 

[pedrosolorzano]

Hi Bygbobbo:

The answer to your question should be the ResultSet class. It let you manage a cursor over a query from a datasource. It also has methods that allows the updating of the underlying database. The constants list gives you an idea about the parametrization and capabilities of this component: CLOSE_CURSORS_AT_COMMIT, CONCUR_READ_ONLY, CONCUR_UPDATABLE, FETCH_FORWARD, FETCH_REVERSE, FETCH_UNKNOWN, HOLD_CURSORS_OVER_COMMIT, etc.

As a member of the JDBC API, it is independent of the datasource (MS SQL 2000 in your case), all you must have is the proper driver for the database. (With the MS SQL db you can also use a JDBC-ODBC bridge).

About the cache time, I should read more about it but, as I understand, the resulting data from the query will stay available until the statement or the connection are closed, so you can manage the staying time through the connection object. But again, I'm not sure.

Hope it helps.

Pedro Andrés Solorzano
Pontificia Universidad Javeriana
Bogotá, Colombia, SurAmérica.

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[Bygbobbo]

anyone have syntax they could share that lets me query a resultset instance.


thanks in advance,

Bygs

 

[sedj]

Why not look at Sun's tutorial ?

http://developer.java.sun.com/developer/onlineTraining/Database/JDBCShortCourse/jdbc/jdbc.html

 

[Bygbobbo]

Maybe, I should be a bit more specific.

Let's say I have created the recordset already

and it has 5 records.

I would like to query these 5 records and create another recordset from the original 5 record recordset without having to connect back to the database.

AKA-- Query of a Query.


Thanks in advance

 

[sedj]

Look at

http://java.sun.com/j2se/1.4.1/docs/api/java/sql/ResultSet.html

for ResultSet manipulation. You can update data within the exisitng ResultSet ...

However I'm not sure what you mean by " create another recordset from the original 5 record recordset ".
A ResultSet is created by the JDBC driver, I don't belive you can 'build your own'. If you need to query the data from your original ResultSet, then I would suggest dumping it a file or some object, and proceeding with further manipulation that way.

Ben

 

[Bygbobbo]

Hmm. I know it can be done.

I just didn't want to re-invent the wheel unless I had to.

 

[JVZ]

Checkout these sites...I think they talk about what you want to do....

http://www.javaworld.com/javaworld/jw-02-2001/jw-0202-cachedrow.html

http://developer.java.sun.com/developer/qow/archive/180/index.jsp

HTH