File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
http://aspose.com/file-tools
The moose likes JDBC and the fly likes Correlated subqueries and performance tips Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Databases » JDBC
Bookmark "Correlated subqueries and performance tips" Watch "Correlated subqueries and performance tips" New topic
Author

Correlated subqueries and performance tips

amit punekar
Ranch Hand

Joined: May 14, 2004
Posts: 516
Hello,
I have gone through some of the threads in this forum.
I have two questions here.
1) have you also explained the correlated subqueries and their usage. Normally questions like nth highest/lowest kind of stuff is common in practise. Can I get elaborative description on this topic in the book? I fairly know this concept but still not very much confident about their use.Also most of the times we use oracle which gives us RowNum which is useful while writing such queries.
2) Secondly are there any simple performance tuning tips provided in the usual Head first style? Would like to see those which comes handy while writing Stored proc or queries.

Regards,
Amit
[ October 17, 2007: Message edited by: amit punekar ]

Regards,
Amit
amit punekar
Ranch Hand

Joined: May 14, 2004
Posts: 516
Hello,
Have I asked anything wrong in the post?
Please correct me if I am wrong because I have not received any answer from yesterday morning.
regards
Amit
Lynn Beighley
author
Ranch Hand

Joined: Sep 12, 2007
Posts: 82
Hi Amit,
There are so many posts that I lost track of yours, I apologize.

1) have you also explained the correlated subqueries and their usage. Normally questions like nth highest/lowest kind of stuff is common in practise. Can I get elaborative description on this topic in the book? I fairly know this concept but still not very much confident about their use.Also most of the times we use oracle which gives us RowNum which is useful while writing such queries.
2) Secondly are there any simple performance tuning tips provided in the usual Head first style? Would like to see those which comes handy while writing Stored proc or queries.


Both correlated and noncorrelated subqueries are covered in the book. I would say that you probably would not get the advanced information you are seeking from the explanation, however. Keep in mind that I'm introducing correlated subqueries to an audience who has never heard of them.

No tuning tips, either. I would think it would need to be in a separate Head First book that takes SQL and applies it to application development.


Lynn Beighley<br />Author, Head First SQL
amit punekar
Ranch Hand

Joined: May 14, 2004
Posts: 516
Hi Lynn,
Thanks for your kind reply and information.

regards,
Amit
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Correlated subqueries and performance tips