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  1. #1
    Join Date
    Apr 2006
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    10

    Unanswered: Can someone help me to answer these oracle questions?

    I need to write a essay to answer the following question, can anyone help me? Thanks

    Question:

    1. How to avoid the update lost issue in an Oracle backed Web Application ?
    2. How do you know your SQL statement will not slow down the application ?
    3. What is binding variable ?
    4. How do you know your JAVA application did not suffer from bind variable ?

  2. #2
    Join Date
    Jan 2004
    Posts
    492
    What have you got so far?
    Oracle OCPI (Certified Practicing Idiot)

  3. #3
    Join Date
    Feb 2004
    Posts
    45
    I think you should start with google, after you figure out why the questions are phrased as they are. It sounds like the person writing the questions has an interest in keeping oracle out of the environment.
    It was working just 5 minutes ago - I promise !

  4. #4
    Join Date
    Apr 2006
    Posts
    10
    OK..let me search by google first, if anyone have sugguestion with these questions, please help me. Thank you for your helping

  5. #5
    Join Date
    May 2005
    Posts
    14
    1. Oracle will only lose an update if an error occurs and it rolls back or the code doesn't commit the change. If the data does not reach the database then it has nothing to do with Oracle.

    2. You need to tune your queries by running an explain plan on them.

    3. Bind variables are a way of passing values to a single query rather than passing thousands of unique queries at the database because each query has a different value hard wired in it.

    4. ?

  6. #6
    Join Date
    Jan 2004
    Posts
    370
    Quote Originally Posted by robdearden
    1. Oracle will only lose an update if an error occurs and it rolls back or the code doesn't commit the change. If the data does not reach the database then it has nothing to do with Oracle.
    I think the question is concerned with the lost update problem which can arise as a result of updating "stale" data on the screen without first locking and checking if it has been changed since you retrieved it.

    AskTom has a discussion here:

    http://asktom.oracle.com/pls/ask/f?p...30562552526857

  7. #7
    Join Date
    Apr 2006
    Posts
    10
    Thanks for helping my questions, robdearden and SkyWriter. The asktom link that you provide is the answer of question 1 that I want.

    But in the second question, can I answer if the SQL statement contain a lot of join table statement, then will slow down the search ?

  8. #8
    Join Date
    Jan 2004
    Posts
    492
    It doesnt matter the number of joins really - it depends on indexing and the explain plan. Look up explain plan and tuning.
    Oracle OCPI (Certified Practicing Idiot)

  9. #9
    Join Date
    May 2005
    Posts
    14
    I agree with ss659 and think question 2 is a little misleading. Any query will slow the application down to some extent. Unless you have made unnecessary joins, the number of joins is determined by the database structure and the data you need to retrieve. The trick is to make sure that the query is as efficient as possible by ensuring that the access path used by Oracle to retrieve the data is correct. This is done using hints in your queries to tell Oracle which order to join your tables, which indexes to use and what join types to apply. An explain plan will show you how the query will execute and therefore allow you to tune it with further hints.

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