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  • How do I add a one-to-one relationship in MYSQL?

    - by alex
    +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | pid | varchar(99) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 1 row in set (0.00 sec) +-------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------------+------+-----+---------+-------+ | pid | varchar(2000) | YES | | NULL | | | recid | varchar(2000) | YES | | NULL | | +-------+---------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) This is my table. pid is just the id of the user. "recid" is a recommended song for that user. I hope to have a list of pid's, and then recommended songs for each person. Of course, in my 2nd table, (pid, recid) would be unique key. How do I do a one-to-one query for this ?

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  • Which database I can used and relationship in it ??

    - by mimo-hamad
    My projece make me confused which I didn't find clear things that make me understand the required database and the relationships in it So, would a super one help me to solve it ?!! ;D this is required: 1) Model the data stored in the database (Identify the entities, roles, relationships, constraints, etc.) 2) Write the Oracle commands to create the database, find appropriate data, and populate the database 3) Write five different queries on your database, using the SELECT/FROM/WHERE construct provided in SQL. Your five queries should illustrate several different aspects of database querying, such as: a. Queries over more than one relation (by listing more than one relation in the FROM clause) b. Queries involving aggregate functions, such as SUM, COUNT, and AVG c. Queries involving complicated selects and joins d. Queries involving GROUP BY, HAVING or other similar functions. e. Queries that require the use of the DISTINCT keyword. And this the condition that we need to determine it to solve the required Q's above : 5) It is desired to develop an Internet membership club to buy products at special prices online. To join, new members must be referred by another existing member of the club. The system will keep the following information for each member: The member ID, referring member, birth date, member name, address, phone, mobile, credit card type, number and expiration date. The items are always shipped to the member's address noted in the membership application. The shipping fees will differ for each order.For each item to be requested, the member will select an item from a long list of possible items. For each item in the database, we store an item ID, an item name, description, and list price. The list price will be different from the actual sale price. The available quantity and the back-ordered quantity (the back-ordered quantity is the quantity on-order by the club from its suppliers) is also noted

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  • How to dynamically order many-to-many relationship in JPA or HQl?

    - by Indrek
    I have a mapping like this: @ManyToMany(cascade = CascadeType.PERSIST) @JoinTable( name="product_product_catalog", joinColumns={@JoinColumn(name="product_catalog", referencedColumnName="product_catalog")}, inverseJoinColumns={@JoinColumn(name="product", referencedColumnName="product")}) public List<Product> products = new ArrayList<Product>(); I can fetch the products for the catalog nicely, but I can't (dynamically) order the products. How could I order them? I probably have to write a many-to-many HQL query with the order-by clause? I though of passing the orderBy field name string to the query, or is there a better solution? Tables are: products, product_catalog, product_product_catalog (associative table) P.S. Using Play! Framework JPASupport for my entities.

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  • Django many-to-many relationship to self with extra data, how do I select from a certain direction?

    - by Jake
    I have some hierarchical data where each Set can have many members and can belong to more than one Set(group) Here are the models: class Set(models.Model): ... groups = models.ManyToManyField('self', through='Membership', symmetrical=False) members = models.ManyToManyField('self', through='Membership', symmetrical=False) class Membership(models.Model): group = models.ForeignKey( Set, related_name='Members' ) member = models.ForeignKey( Set, related_name='Groups' ) order = models.IntegerField( default=-1 ) I want to know how to get all the members or all the groups for a Set instance. I think I can do it as follows, but it's not very logical, can anyone tell me what's going on and how I should be doing it? # This gives me a set of Sets # Which seems to be the groups this Set belongs to set_instance.set_set.all() # These give me a set of Memberships, not Sets set_instance.Members.all() set_instance.Groups.all() # These they both return a set of Sets # which seem to be the members of this one set_instance.members.all() set_instance.groups.all()

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  • In SqlAlchemy, how to ignore m2m relationship attributes when merge?

    - by ablmf
    There is a m2m relation in my models, User and Role. I want to merge a role, but i DO NOT want this merge has any effect on user and role relation-ship. Unfortunately, for some complicate reason, role.users if not empty. I tried to set role.users = None, but SA complains None is not a list. At this moment, I use sqlalchemy.orm.attributes.del_attribute, but I don't know if it's provided for this purpose.

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  • what's the best practice to config Hibernate-Spring for multiple database relationship?

    - by nazila
    We have a main mysql database which all of the applications within our organization need the data within this database. How can I config my java web application to use this database with it's specific database when I use Spring and Hibernate within my application? How can I config JPA annotations for example between CONTRACT table within my database and COUNTRY table within our main database? what's the best practice to do this?

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  • How can one describe a rock-paper-scissors relationship between 3 items?

    - by Madara Uchiha
    Let's say I have the following structure: abstract class Hand {} class Rock extends Hand {} class Paper extends Hand {} class Scissors extends Hand {} The goal is to make a function (or a method) Hand::compareHands(Hand $hand1, Hand $hand2), which would return the winning hand in a rock-paper-scissors match. That would be very easy with a bunch of ifs, but the point is to have a more robust structure, that's relying on polymorphism rather than on procedural code. P.S. this is done in actual production code, if someone is asking. This isn't some sort of challenge or homework. (It's not really rock-paper-scissors, but you get the point).

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  • In which controller do you put the CRUD for the child part of a relationship?

    - by uriDium
    I am using ASP.Net MVC but this probably applies to all MVC patterns in general. My problem, for example I have companies and in each company I have a list of contacts. When I have selected a company I can see its details and a list of the contacts for that company. When I want to add a new contact for that company, should the implementation of that action go into the company controller as an "AddContact" action or should it go into the contact controller into a "New" action and we pass the Company ID in the URL? What is the usual way of dealing with this sort of thing in ASP.Net MVC? Is there a better stategy?

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  • Lite-Javascript Gallery - Can I position the img absolutely in relationship to the lis?

    - by blackessej
    I have a lite-javascript run image gallery. The javascript grabs each element in the list and places it as a background in the parent element. Then the CSS styles the thumbnails as small blocks with a defined height/width. A click-event for each object toggles it’s child’s element’s visibility and adds an “active” class name to the . Using CSS, I'm trying to place the absolutely to make it appear at the same position for each thumb, but it's moving in relation to the thumbs. Here's the CSS: #jgal li { background-position:50% 50%; background-repeat:no-repeat; border:solid #999 4px; cursor:pointer; display:block; float:left; height:60px; width:60px; margin-bottom:14px; margin-right:14px; opacity:0.5; } #jgal li img { position:absolute; top:0px; left:210px; display:none; } And the site: http://www.erisdesigns.net Thanks in advance for any help!

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  • Django: How can I add weight/ordering to a many to many relationship?

    - by Klaas van Schelven
    I'm having Pages with TextBlocks on them. Text Blocks may appear on different pages, pages may have several text blocks on them. Every page may have these blocks in an ordering of it's own. This can be solved by using a separate through parameter. Like so: class TextBlock(models.Model): title = models.CharField(max_length=255) text = models.TextField() class Page(models.Model): textblocks = models.ManyToManyField(TextBlock, through=OrderedTextBlock) class OrderedTextBlock(models.Model): text_block = models.ForeignKey(TextBlock) product_page = models.ForeignKey(ProductPage) weight = models.IntegerField() class Meta: ordering = ('weight',) But I'm not very enthousiastic about the violations of DRY for my app. (There's a lot of ordered ManyToMany relations). Is there a recommended way to go about this?

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  • SQL Database Schema Design For Large 3 Billion Relationship Database.

    - by K-Bell
    Get your geek on. Can you solve this? I am designing a products database for SQL Server 2008 R2 Ed. (not Enterprise Ed.) that will be used to store custom product configurations for over 30,000 distinct products. The database will have up to 500 users at a time. Here is the design problem… Each Product has a collection of Parts (up to 50 parts per product). So if I have 30,000 Products and each of them can have up to 50 Parts, that’s 1.5 million distinct Product-to-Part relationships …or as an equation… 30,000 (Products) X 50 (Parts) = 1.5 million Product-to-Parts records. …and If… Each Part can have up to 2000 finish options (A finish is a paint color). NOTE: Only one finish will be selected by a user at run-time. The 2000 finish options I need to store are the allowed options for a specific part on a specific product. So if I have 1.5 million distinct product-to-part relationships/records and each of those parts can have up to 2,000 finishes that is 3 billion allowable product-to-part-to finish relationships/records …or as an equation… 1.5 million (Parts) x 2,000 (Finishes) = 3 Billion Product-to-Part-to-Finishes records. How can I design this database so that I can execute fast and efficient queries for a specific product and return its list of Parts and all the allowable Finishes for each part without 3 Billion Product-to-Part-to-Finish records? Read time is more important then write time. Please post your thoughts/suggestions if you have experience with large databases. Thanks!

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  • possible to show composition relationship in a diagram generated from PHP source code?

    - by ajsie
    i have tested several UML applications for whether they could show composition relationships in the UML diagrams generated form the PHP source code or not, and the result is they can't. i know that this is a typical problem for PHP cause we don't declare a data type when we code, so it's difficult for the UML applications to know if an instance variable is a reference to an object or not. i also tested nWire with the same result. will there never be applications that could show us a complete map over all object relationships more than just inheritance? i think it's a pity that you can't have a good view over all the relationships for an application. cause when i use an open source solution, i always want to know how the objects are related to each other. maybe we could make comments for the instance variable telling the software that this is an reference to an object? but that would mean that the mapping software is using this solution. i feel its a pity nWire/visual paradigm can't give us a complete map:(

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  • [app-engine-java-groovy] One-to-Many relationship. Select objects from datastore.

    - by Olexandr
    Hi. I've omitted some code(package declarations, imports, other fields) for shortness. I have here simple One-to-Many relation. It worked fine till this moment. @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class Restaurant implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent(mappedBy = "restaurant") List<RestaurantAddress> addresses = new ArrayList<RestaurantAddress>() } //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class RestaurantAddress implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key id @Persistent Restaurant restaurant } Now i need to get(select) all the Restaurants from DB: def getRestaurantsToExport(final String dst, final int count) { String field = restaurantExportFields[dst] return transactionExecute() { PersistenceManager pm -> Query q = pm.newQuery(Restaurant.class) q.filter = "$field == null" q.setRange(0, count) return q.execute() } } But there are on problem - query gives me 12 restaurants(as in DB) but every Restaurant has 0 Address but in Datastore every Restaurant has minimum 2 addresses. Have anyone the same problem or knows the solution ?

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  • Rails ActiveRecord - How to set association save order

    - by Altonymous
    I have a weird relationship that needs to be maintained for legacy processes. I'm trying to figure out how to create the relationship given the new model association. New Relationship Setup Machine has_many MachineReadings has_many Disks has_many DiskReadings Old Relationship Setup Machine has_many MachineReadings has_many DiskReadings has_many Disks The problem is data will come in on the Machine model as nested attributes using the new relationship setup. I need to update the machine_reading_id in the DiskReading model so the old association can continue to be used. I tried doing this via an after_save hook that would traverse back up to the machine and then down to the readings to get the machine_reading.id so I could populate the DiskReading model. However, the associations aren't being saved in the order I would expect. They are saving the Disks & DiskReadings before saving the MachineReadings. So when I go after the machine_reading.id it hasn't been written and thus I am unable to get access to it. For example: #machine_disk_reading.rb after_save :build_old_relationship def build_old_relationship self.machine_reading_id = self.disk.machine.readings.find_by_date_time(self.date_time).id end

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  • How to dynamically order many-to-many relationship with JPA or HQl?

    - by Indrek
    I have a mapping like this: @ManyToMany(cascade = CascadeType.PERSIST) @JoinTable( name="product_product_catalog", joinColumns={@JoinColumn(name="product_catalog", referencedColumnName="product_catalog")}, inverseJoinColumns={@JoinColumn(name="product", referencedColumnName="product")}) public List<Product> products = new ArrayList<Product>(); I can fetch the products for the catalog nicely, but I can't (dynamically) order the products. How could I order them? I probably have to write a many-to-many HQL query with the order-by clause? I though of passing the orderBy field name string to the query, or is there a better solution? Tables are: products, product_catalog, product_product_catalog (associative table) P.S. Using Play! Framework JPASupport for my entities.

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  • c# How to make linq master detail query for 0..n relationship?

    - by JK
    Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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  • How can I achieve this kind of relationship (inheritance, composition, something else)?

    - by Tim
    I would like to set up a foundation of classes for an application, two of which are person and student. A person may or may not be a student and a student is always a person. The fact that a student “is a” person led me to try inheritance, but I can't see how to make it work in the case where I have a DAO that returns an instance of person and I then want to determine if that person is a student and call student related methods for it. class Person { private $_firstName; public function isStudent() { // figure out if this person is a student return true; // (or false) } } class Student extends Person { private $_gpa; public function getGpa() { // do something to retrieve this student's gpa return 4.0; // (or whatever it is) } } class SomeDaoThatReturnsPersonInstances { public function find() { return new Person(); } } $myPerson = SomeDaoThatReturnsPersonInstances::find(); if($myPerson->isStudent()) { echo 'My person\'s GPA is: ', $myPerson->getGpa(); } This obviously doesn't work, but what is the best way to achieve this effect? Composition doesn't sond right in my mind because a person does not “have a” student. I'm not looking for a solution necessarily but maybe just a term or phrase to search for. Since I'm not really sure what to call what I'm trying to do, I haven't had much luck. Thank you!

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  • Use SQL to clone data in two tables that have a 1-1 relationship with each other

    - by AmoebaMan17
    Using MS SQL 2005, Table 1 ID | T1Value | T2ID | GroupID ---------------------------------- 1 | a | 10 | 1 2 | b | 11 | 1 3 | c | 12 | 1 4 | a | 22 | 2 Table 2 ID | T2Value ---------------- 10 | H 11 | J 12 | K 22 | H I want to clone the data for GroupID == 1 into a new GroupID so that I result with the following: Table 1 ID | T1Value | T2ID | GroupID ---------------------------------- 1 | a | 10 | 1 2 | b | 11 | 1 3 | c | 12 | 1 4 | a | 22 | 2 5 | a | 23 | 3 6 | b | 24 | 3 7 | c | 25 | 3 Table 2 ID | T2Value ---------------- 10 | H 11 | J 12 | K 22 | H 23 | H 24 | J 25 | K I've found some SQL clone patterns that allow me to clone data in the same table well... but as I start to deal with cloning data in two tables at the same time and then linking up the new rows correctly... that's just not something I feel like I have a good grasp of. I thought I could do some self-joins to deal with this, but I am worried in the cases where the non-key fields have the same data in multiple rows.

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