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  • World's Most Challening MySQL SQL Query (least I think so...)

    - by keruilin
    Whoever answers this question can claim credit for solving the world's most challenging SQL query, according to yours truly. Working with 3 tables: users, badges, awards. Relationships: user has many awards; award belongs to user; badge has many awards; award belongs to badge. So badge_id and user_id are foreign keys in the awards table. The business logic at work here is that every time a user wins a badge, he/she receives it as an award. A user can be awarded the same badge multiple times. Each badge is assigned a designated point value (point_value is a field in the badges table). For example, BadgeA can be worth 500 Points, BadgeB 1000 Points, and so on. As further example, let's say UserX won BadgeA 10 times and BadgeB 5 times. BadgeA being worth 500 Points, and BadgeB being worth 1000 Points, UserX has accumulated a total of 10,000 Points ((10 x 500) + (5 x 1000)). The end game here is to return a list of top 50 users who have accumulated the most badge points. Can you do it?

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  • How do I find the .max of an attribute value among a group of different Models?

    - by Angela
    Hi, everyone: I am also open to just straight-up refactoring what I'm finding to be pretty repetitive, but to give a baseline of how it's working.... I have for every contact a Campaign, which has_many of three types of Models: Email, Call, and Letter. When an Email (Call or Letter) has been executed for a specific contact, I have a Contact_Email(_or_Call_or_Letter) which belongs to both the Contact and the Model (Email_or_Call_or_Letter). Each Contact_Email for example pairing has a :date_sent attribute. So does each Contact_Call and Contact_Letter. How do I find the latest of all of them? Here is the code I wrote that can find the latest Email and my finding retyping similar code for Call and Letter, but then stuck on how to do a .max on all of them: def last_email(contact) #get campaign the contact belongs to @campaign = Campaign.find_by_id(contact.campaign_id) @last_email = ContactEmail.find(:last, :conditions => "contact_id = #{contact.id}", :order => "date_sent DESC") @last_call = ContactCall.find(:last, :conditions => "contact_id = #{contact.id}", :order => "date_sent DESC") @last_letter = ContactLetter.find(:last, :conditions => "contact_id = #{contact.id}", :order => "date_sent DESC") # how do I get the latest of all of these to display? if @last_sent_email.nil? return "no email sent" else return @last_sent_email.date_sent end end Question 1: With what I have, how can I find effectively @last_event given I can find the last Email, last Call, and last Letter for every contact? Question 2: How can I remove the repetitive code that I have to write for each Model?

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  • Getting the ranking of a photo in SQL

    - by Jake Petroules
    I have the following tables: Photos [ PhotoID, CategoryID, ... ] PK [ PhotoID ] Categories [ CategoryID, ... ] PK [ CategoryID ] Votes [ PhotoID, UserID, ... ] PK [ PhotoID, UserID ] A photo belongs to one category. A category may contain many photos. A user may vote once on any photo. A photo can be voted for by many users. I want to select the ranks of a photo (by counting how many votes it has) both overall and within the scope of the category that photo belongs to. The count of SELECT * FROM Votes WHERE PhotoID = @PhotoID being the number of votes a photo has. I want the resulting table to have generated columns for overall rank, and rank within category, so that I may order the results by either. So for example, the resulting table from the query should look like: PhotoID VoteCount RankOverall RankInCategory 1 48 1 7 3 45 2 5 19 33 3 1 2 17 4 3 7 9 5 5 ... ...you get the idea. How can I achieve this? So far I've got the following query to retrieve the vote counts, but I need to generate the ranks as well: SELECT PhotoID, UserID, CategoryID, DateUploaded, (SELECT COUNT(CommentID) AS Expr1 FROM dbo.Comments WHERE (PhotoID = dbo.Photos.PhotoID)) AS CommentCount, (SELECT COUNT(PhotoID) AS Expr1 FROM dbo.PhotoVotes WHERE (PhotoID = dbo.Photos.PhotoID)) AS VoteCount, Comments FROM dbo.Photos

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  • Initialize child models at model creation

    - by Antoine
    I have a model Entree which belongs to a model Vin, which itself belongs to a model Producteur. On the form for Entree creation/edition, I want to allow the user to define the attributes for parent Vin and Producteur to create them, or retrieve them if they exist (retrieval based on user input). For now I do the following in Entree new and edit actions: @entree = Entree.new @entree.vin = Vin.new @entree.vin.producteur = Producteur.new and use fields_for helper in the form,and that works. But I intend to have much more dependencies with more models, so I want to keep it DRY. I defined a after_initialize callback in Vin model which does the producteur initialization: class Vin < ActiveRecord::Base after_initialize :vin_setup def vin_setup producteur = Producteur.new end end and remove the producteur.new from the controller. However, get an error on new action: undefined method `model_name' for NilClass:Class for the line in the form that says <%= fields_for @entree.vin.producteur do |producteur| %> I guess that means the after_initialize callback doesn't act as I expect it. Is there something I'm missing? Also, I get the same error if I define a after_initialize method in the Vin model instead of definiing a callback.

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  • How do you unit-test a method with complex input-output

    - by Dan
    When you have a simple method, like for example sum(int x, int y), it is easy to write unit tests. You can check that method will sum correctly two sample integers, for example 2 + 3 should return 5, then you will check the same for some "extraordinary" numbers, for example negative values and zero. Each of these should be separate unit test, as a single unit test should contain single assert. What do you do when you have a complex input-output? Take a Xml parser for example. You can have a single method parse(String xml) that receives the String and returns a Dom object. You can write separate tests that will check that certain text node is parsed correctly, that attributes are parsed OK, that child node belongs to parent etc. For all these I can write a simple input, for example <root><child/></root> that will be used to check parent-child relationships between nodes and so on for the rest of expectations. Now, take a look at follwing Xml: <root> <child1 attribute11="attribute 11 value" attribute12="attribute 12 value">Text 1</child1> <child2 attribute21="attribute 21 value" attribute22="attribute 22 value">Text 2</child2> </root> In order to check that method worked correctly, I need to check many complex conditions, like that attribute11 and attribute12 belong to element1, that Text 1 belongs to child1 etc. I do not want to put more than one assert in my unit-test. How can I accomplish that?

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  • Handling Denormalized Schema with Eclipselink

    - by iamrohitbanga
    Hello All I have a denormalized table containing employee information. The fields are employee id, name and department name. The primary key is a composite one consisting of all three fields. An employee can belong to multiple departments. I want to read/write the objects in the table using the Eclipselink Dynamic Persistence API (which is infact a wrapper on top of JPA descriptors etc.). Example Data: 1 e1 dep1 2 e1 dep2 3 e2 dep1 4 e2 dep3 5 e3 dep1 5 e3 dep2 5 e3 dep3 A normal ReadAllQuery (select query) on the table returns a DynamicEntity corresponding to each row in the table. However I want to club all entities based on the emp id and return all the departments he belongs to as a list. I can merge the entities after retrieving them but if I can use some Eclipselink feature out of the box then it would be better. One way to do the read is the following: I create two dynamic types corresponding to employee: Having id,name as the primary key Having id, department as the primary key, I create a OneToManyMapping from the first type to the second one. Then when I query the first type it does return the departments to which employee belongs as a list of DynamicEntity of the second type. This satisfies the read scenario. Is there a better way of doing this? Is this inherently supported by Eclipselink or JPA? I cannot get the same dynamic type configuration working for the write scenario. This is because when I write the changes using the writeObject method of UnitOfWork, it generates insert queries which enter the following entries in the table id name department 102 emp_102 102 st 102 dep_102 102 dep_102 102 dep_102 instead of: id name department 102 emp_102 st 102 emp_102 dep_102 102 emp_102 dep_102 102 emp_102 dep_102 Is there any way I can get write to work with this schema using eclipselink? I want to avoid doing the heavy lifting of merging the rows for such a denormalized schema or generating each row before doing a write. Is there no clean way of doing this using Eclipselink or JPA? Thanks in Advance.

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  • UDP security and identifying incoming data.

    - by Charles
    I have been creating an application using UDP for transmitting and receiving information. The problem I am running into is security. Right now I am using the IP/socketid in determining what data belongs to whom. However, I have been reading about how people could simply spoof their IP, then just send data as a specific IP. So this seems to be the wrong way to do it (insecure). So how else am I suppose to identify what data belongs to what users? For instance you have 10 users connected, all have specific data. The server would need to match the user data to this data we received. The only way I can see to do this is to use some sort of client/server key system and encrypt the data. I am curious as to how other applications (or games, since that's what this application is) make sure their data is genuine. Also there is the fact that encryption takes much longer to process than unencrypted. Although I am not sure by how much it will affect performance. Any information would be appreciated. Thanks.

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  • MySQL Join Question

    - by rbaker86
    Hi i'm struggling to write a particular MySQL Join Query. I have a table containing product data, each product can belong to multiple categories. This m:m relationship is satisfied using a link table. For this particular query I wish to retrieve all products belonging to a given category, but with each product record, I also want to return the other categories that product belongs to. Ideally I would like to achieve this using an Inner Join on the categories table, rather than performing an additional query for each product record, which would be quite inefficient. My simplifed schema is designed roughly as follows: products table: product_id, name, title, description, is_active, date_added, publish_date, etc.... categories table: category_id, name, title, description, etc... product_category table: product_id, category_id I have written the following query, which allows me to retrieve all the products belonging to the specified category_id. However, i'm really struggling to work out how to retrieve the other categories a product belongs to. SELECT p.product_id, p.name, p.title, p.description FROM prod_products AS p LEFT JOIN prod_product_category AS pc ON pc.product_id = p.product_id WHERE pc.category_id = $category_id AND UNIX_TIMESTAMP(p.publish_date) < UNIX_TIMESTAMP() AND p.is_active = 1 ORDER BY p.name ASC I'd be happy just retrieving the category id's releated to each returned product row, as I will have all category data stored in an object, and my application code can take care of the rest. Many thanks, Richard

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  • create child nodes from sibling nodes until a different sibbling occurs.

    - by user364939
    Hi does anyone know what the xsl would look like to transform this XML. There can be N nte's after pid and N nte's after pv1. The structure is guaranteed in that all nte that follows pid belongs to pid and all nte following pv1 belongs to pv1. From: <pid> </pid> <nte> <nte-1>1</nte-1> <nte-3>Note 1</nte-1> </nte> <nte></nte> <pv1></pv1> <nte> </nte> into: <pid> <nte> <nte-1>1</nte-1> <nte-3>Note 1</nte-1> </nte> <nte> </nte> </pid> <pv1> <nte> </nte> </pv1> Thanks!

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  • Multisite Enabling a Table

    - by Joe Fitzgibbons
    I am creating a table (table A) that will have a number of columns(of course) and there will be another table (table B) that holds metadata associated to rows in table A. I am working with a multi site implementation that has one database for the whole shabang. Rows in table A could belong to any number of sites but must belong to at least one. The problem I have is I am not sure what the best practice is for defining what site each row in table A belongs to. I want performance and scalability. There is no finite number of sites going forward. Rows in table A could belong to any number of sites in the future. Right now there are only 3. My initial thoughts are to have a primary site ID in Table A and then metadata in table B will have rows defining additional sites as needed. Another thought is to have a column in Table A for each site and it is a boolean as to wether it belongs to that site. Lastly I have thought about having another table to map rows in Table A to each site. What is the best way to associate rows in a table with any number of sites with performance and scalability in mind?

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  • esx backup usb disk

    - by maruti
    my server has a disk error, unfortunately RAID-0. So i am planning to boot it off CD (partedmagic) and copy the VMs to a USB disk. File system is VMFS (esxi4) once the damaged disk is replaced back could the data be restored back? this server has two datastores this bad disk belongs to store-1. please suggest any better ways or tools. thanks in advance

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  • Validating GPG key signature authenticity

    - by Dor
    I'm trying to validate the integrity of my httpd-2.2.17.tar.gz image. I followed the steps written in the following pages: http://httpd.apache.org/download.cgi#verify http://httpd.apache.org/dev/verification.html#Validating But I got: WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. What I need to do in order to verify the authenticity of the key?

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  • Nautilus cannot move to trash

    - by amorfis
    Thing takes place on ubuntu. I want to move a file to trash. I am not the owner of the file, but file belongs to root:samba, and I am member of samba group, and file permissions are rwxrw-r-- There is message "Cannot move file to trash, do you want to delete immediately?". Nothing more. Why can't I move it to trash?

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  • Arp tries on various *nix based systems.

    - by salparadise
    Does anyone know what determines the amount of arp tries a router will make? I have different behaviors with two devices, if I try to traceroute to a non-existent host on a subnet that belongs to an interface on the router, a Linux box will try to arp 3 times and then return a host un-reacheable icmp message. Junos will continuosly try to arp and not return anything. Is there a sysctl value that determines this or anything at all.

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  • can i find the web hosting company from an ip address ?

    - by ufk
    Hiya. i really hope this question suites serverfault, if not my apologies! I have an ip address, is there a way to find the web hosting service that this ip address belongs to ? I tried using whois and traceroute but no luck so far. the case is that my friend bought a domain and storage several years ago and he can't remember where he bought the storage from. thanks!

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  • MB with CPU and power supply - can be turned on but not off

    - by COcodrilo
    Hi, Not sure whether this question belongs here, I hope so. I have just bought a motherboard and CPU. I have installed the CPU, cooler and connected to CPUFAN on the MB. I have plugged the power supply to MB and the cable from "ON" button to pins named "PWR" and the LEDs. However when I turn on the PC, both HDD and POWER leds are continously on and the PC cannot be turned out. What could I be missing?

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  • Oracle 10 g - Unable to free up space in tablespace

    - by Bruno Rothgiesser
    The tablespace in Oracle 10g is almost 100% used. Size (MB) = 571,768.0 Used (MB) = 571,534.0 I just deleted (and committed) thousands of records in a table that belongs to a schema associated with that tablespace. Surprisingly, no space was freed up according to the Tablespaces page on Enterprise Manager. Question: is there anything that I need to do to force Oracle to release the space corresponding to the deleted records?

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  • How to poll the username, when having the UID?

    - by JMW
    we're using ldap with sssd for the usermanagement, so our users are not in the "/etc/passwd" Unfortunately, ps just shows the UIDs: [root@xyz ~]# id jmw uid=1582(jmw) gid=1582(jmw) groups=1582(jmw), 1000(admins) [root@xyz ~]# ps aux [..cutting some output..] 1582 26794 25.0 0.4 190420 38508 ? S 12:15 0:00 /usr/bin/php-cgi -c php.ini [..cutting some output..] How can i poll the username, that belongs to a UID? ( a grep ':1582:' /etc/passwd doesn't work ;-) )

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  • What is the most secure way to allow a user read access to a log file?

    - by gAMBOOKa
    My application requires read access to /var/log/messages, which belongs to user and group root. What is the minimal exposure level required on /var/log/messages so my application can read it? Presently, my plan is to change the group ownership of /var/log/messages to a new group, and add root and my application user to it, but this would also give the application write privileges to /var/log/messages. OS: Centos 5.5

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  • MB with CPU and power supply - can be turned on but not off [closed]

    - by COcodrilo
    Hi, Not sure whether this question belongs here, I hope so. I have just bought a motherboard and CPU. I have installed the CPU, cooler and connected to CPUFAN on the MB. I have plugged the power supply to MB and the cable from "ON" button to pins named "PWR" and the LEDs. However when I turn on the PC, both HDD and POWER leds are continously on and the PC cannot be turned out. What could I be missing?

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  • Are EC2 security group changes effective immediately for running instances?

    - by Jonik
    I have an EC2 instance running, and it belongs to a security group. If I add a new allowed connection to that security group through AWS Management Console, should that change be effective immediately? Or perhaps only after restart of the instance? In my case, I'm trying to allow access to PostgreSQL's default port (tcp 5432 5432 0.0.0.0/0), and I'm not sure if it's the EC2 firewall or PostgreSQL's settings that are refusing the connection.

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  • Router reporting failed admin login attempts from home server

    - by jeffora
    I recently noticed in the logs of my home router that it relatively regularly lists the following entry: [admin login failure] from source 192.168.0.160, Monday, June 20,2011 18:13:25 192.168.0.160 is the internal address of my home server, running Windows Home Server 2011. Is there anyway I can find out what specifically is trying to login to the router? Or is there some explanation for this behaviour? (not sure if this belongs here or on superuser...)

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