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Correlated subqueries and performance tips

 
amit punekar
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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 ]
 
amit punekar
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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
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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.
 
amit punekar
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Hi Lynn,
Thanks for your kind reply and information.

regards,
Amit
 
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