I wonder if this can be done with SQL...
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 5 of 5

Thread: I wonder if this can be done with SQL...

  1. #1
    Join Date
    Jan 2010
    Posts
    3

    I wonder if this can be done with SQL...

    Hi people

    I wonder if anyone can help (I hope I have the right forum for this, apologies if I donīt).

    I am scratching my head with this one....

    I have a db table called transactions.
    A transaction record: tran_id, number_of_points_given, date_given....

    (The field number_of_points_given can hold a value from 1 to 10)


    I also have prize table with records of prizes, e.g:
    A prize record: pr_id, pr_desc, pr_num_points_reqd, ....

    When a prize is claimed, I need to calculate the number of transaction records that need to be deleted. The value from the prize claimed (prize.number_of_points_given) should equal the sum of X number of transaction recordsī number_of_points_given.

    For example, a prize is worth 10 points. A customer has 100 transaction records, each with a value in their num_points_given of 1-10. The customer claims the prize so only X transaction records need to deleted where X is the sum of the number_of_points_given in the X transaction records AND this number_of_points_given total equals the prize.num_points_reqd.

    So the number of transaction records to be deleted is determined by not only the number_of_points_reqd but the sum of the transaction recordsī number_of_points_given fields.


    If the transaction records were each just worth 1 point, I could limit the number of transactions selected by the prize.number_points_reqd.


    Any tips would be great!

  2. #2
    Join Date
    Jan 2010
    Posts
    3

    a bit more clarification - if it helps! :)

    example:

    Customer A has these transaction records:

    trans_id number_of_points_given
    1 1
    2 5
    3 5
    4 2
    5 1

    The prize that this customer A claims is worth 10 points (prize.number_points_reqd = 10)

    So, I only want to delete a number of transaction records where their combined number_of_points_given = prize.number_points_reqd (10), no more, no less

  3. #3
    Join Date
    Mar 2007
    Location
    Ft. Lauderdale, FL
    Posts
    3,554
    Absolutely.

    For each PRIZE row load in a cursor all TRANSACTIONS rows belonging to the current PRIZE.customer then loop into the cursor doing your math and issuing deletes on TRANSACTIONS table when appropriate.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

  4. #4
    Join Date
    Jan 2010
    Posts
    3

    Thank you for the quick response, but (isnīt there always a but...)...

    Okay, thanks for your quick response,

    So I should:
    • load all transaction rows belonging to the customer who has won the prize into a cursor
      .

    • Then, I should loop through the cursor aggregating the values of the transaction num_points_given.

    • when I get to equal the prize.num_points_reqd I delete the transaction records marked and break out (as it where) of the cursor.


    Ok, (I think). Two points though: firstly I am new to cursors so I will have to look up how to use them. Secondly, I am actually testing on MySQL (sorry if I shouldnīt have posted here), but any further clarifications would be great, thanks again.

  5. #5
    Join Date
    Mar 2007
    Location
    Ft. Lauderdale, FL
    Posts
    3,554
    Quote Originally Posted by GoldenCockerel View Post
    ... I am actually testing on MySQL
    I see, just a small detail... LOL Okay, since MySQL provides support for both storedprocs and cursors, general logic would be the same. For MySQL specifics better to look for a MySQL forum.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width