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  • How can I create a small relational database in MySQL?

    - by Sergio Tapia
    I need to make a small database in MySQL that has two tables. Clothes and ClotheType Clothes has: ID, Name, Color, Brand, Price, ClotheTypeID ClotheType has: ID, Description In Microsoft SQL it would be: create table Clothes( id int, primary key(id), name varchar(200), color varchar(200), brand varchar(200), price varchar(200), clothetypeid int, foreign key clothetypeid references ClotheType(id) ) I need this in MySQL.

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  • How do I use on delete cascade in mysql?

    - by Marius
    I have a database of components. Each component is of a specific type. That means there is a many-to-one relationship between a component and a type. When I delete a type, I would like to delete all the components which has a foreign key of that type. But if I'm not mistaken, cascade delete will delete the type when the component is deleted. Is there any way to do what I described?

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  • When/Why to use Cascading in SQL Server?

    - by Joel Coehoorn
    When setting up foreign keys in SQL Server, under what circumstances should you have it cascade on delete or update, and what is the reasoning behind it? This probably applies to other databases as well. I'm looking most of all for concrete examples of each scenario, preferably from someone who has used them successfully.

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  • Entity Framework Adding new record with foreign key constraint

    - by Brono The Vibrator
    In an effort to learn the entity framework I have created two tables in a one to many relationship. The one table (Author) has the following fields - AuthorID, FirstName, LastName. The many table (Payroll) has the following fields - PayrollID, AuthorID, Salary. I have CRUD stored procdures for insert, update and delete. What I am tying to figure-out is how to add new payroll records to the payroll table.

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  • JQGrid: Dropdown for selecting items from a foreign table - DataValueField vs DataTextField

    - by Herb Caudill
    Suppose Items and ItemTypes have numeric primary keys ItemID and ItemTypeID. Each Item is assigned an ItemType. I have a JQGrid to edit Items. When not in edit mode, I would like to see the name of the ItemType, not the ItemTypeID: TYPE | TITLE -----------+-------------------- Category A | Item 1 Category A | Item 2 Category B | Item 3 Category B | Item 4 In edit mode, I want to see a dropdown that displays the ItemType text, but that returns the ItemTypeID to the server. Here's what I have so far (using the ASP.NET wrapper for JQGrid): <trirand:jqgrid id="Grid1" runat="server" ... > <columns> <trirand:jqgridcolumn datafield="ItemID" editable="false" visible="false" width="50" primarykey="true" /> <trirand:jqgridcolumn datafield="ItemTypeID" editable="true" edittype="DropDown" editorcontrolid="ItemTypes" /> <trirand:jqgridcolumn datafield="Title" editable="true" sortable="true" /> ... </columns> </trirand:jqgrid> <asp:sqldatasource runat="server" id="ItemTypesDatasource" connectionstring="<%$ ConnectionStrings:Main %>" selectcommand="Select ItemTypeID,Title from ItemTypes order by Title" /> <asp:dropdownlist runat="server" id="ItemTypes" datasourceid="ItemTypesDatasource" datavaluefield="ItemTypeID" datatextfield="Title" /> The problem is that when not in edit mode, it displays the numeric ItemTypeID, rather than the text labels: TYPE | TITLE -----------+-------------------- 100123 | Item 1 100123 | Item 2 100124 | Item 3 100124 | Item 4 Is there any way to have JQGrid respect the distinction between DataValueField and DataTextField? (Either using the jQuery API or the ASP.NET plugin.)

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  • One-to-one Mapping issue with NHibernate/Fluent: Foreign Key not updateing

    - by Trevor
    Summary: Parent and Child class. One to one relationship between the Parent and Child. Parent has a FK property which references the primary key of the Child. Code as follows: public class NHTestParent { public virtual Guid NHTestParentId { get; set; } public virtual Guid ChildId { get { return ChildRef.NHTestChildId; } set { } } public virtual string ParentName { get; set; } protected NHTestChild _childRef; public virtual NHTestChild ChildRef { get { if (_childRef == null) _childRef = new NHTestChild(); return _childRef; } set { _childRef = value; } } } public class NHTestChild { public virtual Guid NHTestChildId { get; set; } public virtual string ChildName { get; set; } } With the following Fluent mappings: Parent Mapping Id(x => x.NHTestParentId); Map(x => x.ParentName); Map(x => x.ChildId); References(x => x.ChildRef, "ChildId").Cascade.All(); Child Mapping: Id(x => x.NHTestChildId); Map(x => x.ChildName); If I do something like (pseudo code) ... HTestParent parent = new NHTestParent(); parent.ParentName = "Parent 1"; parent.ChildRef.ChildName = "Child 1"; nhibernateSession.SaveOrUpdate(aParent); Commit; ... I get an error: "Invalid index 3 for this SqlParameterCollection with Count=3" If I change the parent 'References' line as follows (i.e. provide the name of the child property I'm pointing at): References(x => x.ChildRef, "ChildId").PropertyRef("NHTestChildId").Cascade.All(); I get the error: "Unable to resolve property: NHTestChildId" So, I tried the 'HasOne()' reference setting, as follows: HasOne<NHTestChild>(x => x.ChildRef).ForeignKey("ChildId").Cascade.All().Fetch.Join(); This results in the save working, but the load fails to find the child. If I inspect the SQL Nhibernate produces I can see that NHibernate is assuming the Primary key of the parent is the link to the child (i.e. load join condition is "parent.NHTestParentId = child.NHTestChildId). The 'ForeignKey' specified appears to be ignored. I can set any value and no error occurs - the join just always fails and no child is returned. I've tried a number of slight variations on the above. It seems like it should be a simple thing to achieve. Any ideas?

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  • Django: UserProfile with Unique Foreign Key in Django Admin

    - by lazerscience
    Hi, I have extended Django's User Model using a custom user profile called UserExtension. It is related to User through a unique ForeignKey Relationship, which enables me to edit it in the admin in an inline form! I'm using a signal to create a new profile for every new user: def create_user_profile(sender, instance, created, **kwargs): if created: try: profile, created = UserExtension.objects.get_or_create(user=instance) except: pass post_save.connect(create_user_profile, sender=User) (as described here for example: http://stackoverflow.com/questions/44109/extending-the-user-model-with-custom-fields-in-django) The problem is, that, if I create a new user through the admin, I get an IntegritiyError on saving "column user_id is not unique". It doesnt seem that the signal is called twice, but i guess the admin is trying to save the profile AFTERWARDS? But I need the creation through signal if I create a new user in other parts of the system!

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  • POJOs for Composite Primary Key from Foreign Key

    - by Gaurav
    hi, I have table in database that has only two columns and these two colums are FK references. they have made these two colums as composite primarykey. table structure Table A [ A_id PK Description ] Table B [ B_Id PK Description ] Table A_B_Pemissiom [ A_id (FK table A) B_Id (FK table B) PrimaryKey ( A_id,B_Id ) ] Can anyone help , I tried several ways and none of them works. Can anyone tell a working Hibernate mapping solution using annotations ? Thanks, Gaurav

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  • Fluent NHibernate - How to map a non nullable foreign key that exists in two joined tables

    - by vakman
    I'm mapping a set of membership classes for my application using Fluent NHibernate. I'm mapping the classes to the asp.net membership database structure. The database schema relevant to the problem looks like this: ASPNET_USERS UserId PK ApplicationId FK NOT NULL other user columns ... ASPNET_MEMBERSHIP UserId PK,FK ApplicationID FK NOT NULL other membership columns... There is a one to one relationship between these two tables. I'm attempting to join the two tables together and map data from both tables to a single 'User' entity which looks like this: public class User { public virtual Guid Id { get; set; } public virtual Guid ApplicationId { get; set; } // other properties to be mapped from aspnetuser/membership tables ... My mapping file is as follows: public class UserMap : ClassMap<User> { public UserMap() { Table("aspnet_Users"); Id(user => user.Id).Column("UserId").GeneratedBy.GuidComb(); Map(user => user.ApplicationId); // other user mappings Join("aspnet_Membership", join => { join.KeyColumn("UserId"); join.Map(user => user.ApplicationId); // Map other things from membership to 'User' class } } } If I try to run with the code above I get a FluentConfiguration exception Tried to add property 'ApplicationId' when already added. If I remove the line "Map(user = user.ApplicationId);" or change it to "Map(user = user.ApplicationId).Not.Update().Not.Insert();" then the application runs but I get the following exception when trying to insert a new user: Cannot insert the value NULL into column 'ApplicationId', table 'ASPNETUsers_Dev.dbo.aspnet_Users'; column does not allow nulls. INSERT fails. The statement has been terminated. And if I leave the .Map(user = user.ApplicationId) as it originally was and make either of those changes to the join.Map(user = user.ApplicationId) then I get the same exception above except of course the exception is related to an insert into the aspnet_Membership table So... how do I do this kind of mapping assuming I can't change my database schema?

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  • Django: Summing values of records grouped by foreign key

    - by Dan0
    Hi there In django, given the following models (slightly simplified), I'm struggling to work out how I would get a view including sums of groups class Client(models.Model): api_key = models.CharField(unique=True, max_length=250, primary_key=True) name = models.CharField(unique=True, max_length=250) class Purchase(models.Model): purchase_date = models.DateTimeField() client = models.ForeignKey(SavedClient, to_field='api_key') amount_to_invoice = models.FloatField(null=True) For a given month, I'd like to see e.g. April 2010 For Each Client that purchased this month: * CLient: Name * Total amount of Purchases for this month * Total cost of purchases for this month For each Purchase made by client: * Date * Amount * Etc I've been looking into django annotation, but can't get my head around how to sum values of a field for a particular group over a particular month and send the information to a template as a variable/tag. Any info would be appreciated

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  • Linq to Entities and POCO foreign key relations mapping (1 to 0..1) problem

    - by brainnovative
    For my ASP.NET MVC 2 application I use Entity Framework 1.0 as my data access layer (repository). But I decided I want to return POCO. For the first time I have encountered a problem when I wanted to get a list of Brands with their optional logos. Here's what I did: public IQueryable<Model.Products.Brand> GetAll() { IQueryable<Model.Products.Brand> brands = from b in EntitiesCtx.Brands.Include("Logo") select new Model.Products.Brand() { BrandId = b.BrandId, Name = b.Name, Description = b.Description, IsActive = b.IsActive, Logo = /*b.Logo != null ? */new Model.Cms.Image() { ImageId = b.Logo.ImageId, Alt = b.Logo.Alt, Url = b.Logo.Url }/* : null*/ }; return brands; } You can see in the comments what I would like to achieve. It worked fine whenever a Brand had a Logo otherwise it through an exception that you can assign null to the non-nullable type int (for Id). My workaround was to use nullable in the POCO class but that's not natural - then I have to check not only if Logo is null in my Service layer or Controllers and Views but mostly for Logo.ImageId.HasValue. It's not justified to have a non null Logo property if the id is null. Can anyone think of a better solution?

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  • Django foreign key question

    - by Hulk
    All, i have the following model defined, class header(models.Model): title = models.CharField(max_length = 255) created_by = models.CharField(max_length = 255) def __unicode__(self): return self.id() class criteria(models.Model): details = models.CharField(max_length = 255) headerid = models.ForeignKey(header) def __unicode__(self): return self.id() class options(models.Model): opt_details = models.CharField(max_length = 255) headerid = models.ForeignKey(header) def __unicode__(self): return self.id() AND IN MY VIEWS I HAVE p= header(title=name,created_by=id) p.save() Now the data will be saved to header table .My question is that for this id generated in header table how will save the data to criteria and options table..Please let me know.. Thanks..

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  • Django Foreign key queries

    - by Hulk
    In the following model: class header(models.Model): title = models.CharField(max_length = 255) created_by = models.CharField(max_length = 255) def __unicode__(self): return self.id() class criteria(models.Model): details = models.CharField(max_length = 255) headerid = models.ForeignKey(header) def __unicode__(self): return self.id() class options(models.Model): opt_details = models.CharField(max_length = 255) headerid = models.ForeignKey(header) def __unicode__(self): return self.id() If there is a row in the database for table header as Id=1, title=value-mart , createdby=CEO How do i query criteria and options tables to get all the values related to header table id=1 Also can some one please suggest a good link for queries examples, Thanks..

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  • Django South Foreign Keys referring to pks with Custom Fields

    - by Rory Hart
    I'm working with a legacy database which uses the MySQL big int so I setup a simple custom model field to handle this: class BigAutoField(models.AutoField): def get_internal_type(self): return "BigAutoField" def db_type(self): return 'bigint AUTO_INCREMENT' # Note this won't work with Oracle. This works fine with django south for the id/pk fields (mysql desc "| id | bigint(20) | NO | PRI | NULL | auto_increment |") but the ForeignKey fields in other models the referring fields are created as int(11) rather than bigint(20). I assume I have to add an introspection rule to the BigAutoField but there doesn't seem to be a mention of this sort of rule in the documentation (http://south.aeracode.org/docs/customfields.html). Update: Currently using Django 1.1.1 and South 0.6.2

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  • Django model: Reference foreign key table in __unicode__ function for admin

    - by pa
    Example models: class Parent(models.Model): name = models.CharField() def __unicode__(self): return self.name class Child(models.Model): parent = models.ForeignKey(Parent) def __unicode__(self): return self.parent.name # Would reference name above I'm wanting the Child.unicode to refer to Parent.name, mostly for the admin section so I don't end up with "Child object" or similar, I'd prefer to display it more like "Child of ". Is this possible? Most of what I've tried hasn't worked unfortunately.

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  • Django foreign key error

    - by Hulk
    In models the code is as, class header(models.Model): title = models.CharField(max_length = 255) created_by = models.CharField(max_length = 255) def __unicode__(self): return self.id() class criteria(models.Model): details = models.CharField(max_length = 255) headerid = models.ForeignKey(header) def __unicode__(self): return self.id() In views, p_l=header.objects.filter(id=rid) for rows in row_data: row_query =criteria(details=rows,headerid=p_l) row_query.save() In row_query =criteria(details=rows,headerid=p_l) there is an error saying 'long' object is not callable in models.py in __unicode__, What is wrong in the code Thanks..

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  • Ruby on Rails ActiveRecord: eager loading issue with foreign and primary key

    - by Krishnaswamy Subramanian
    The eager loading on Ruby on Rails is not working properly for the following scenario. First we had a model called marks which has the following fields id, student, subject, mark the student is a string column which has the active directory login value, later on for reporting functionality we introduce another table called user which has the following fields id, ad_name, full_name Now on the Mark model, we have added the belongs to class belongs_to :student_details, :class_name = "User", :foreign_key = "student", :primary_key = "ad_name" and when loading using the ActiveRecord's find method we are passing in the include conditon for eager loading Marks.find(:all, :include = :reserved_user) but when the find is executed, for each and every mark a student select query executed. Is this a known bug in ROR? or am i missing something?

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  • MySQL nested set hierarchy with foreign table

    - by Björn
    Hi! I'm using a nested set in a MySQL table to describe a hierarchy of categories, and an additional table describing products. Category table; id name left right Products table; id categoryId name How can I retrieve the full path, containing all parent categories, of a product? I.e.: RootCategory > SubCategory 1 > SubCategory 2 > ... > SubCategory n > Product Say for example that I want to list all products from SubCategory1 and it's sub categories, and with each given Product I want the full tree path to that product - is this possible? This is as far as I've got - but the structure is not quite right... select parent.`name` as name, parent.`id` as id, group_concat(parent.`name` separator '/') as path from categories as node, categories as parent, (select inode.`id` as id, inode.`name` as name from categories as inode, categories as iparent where inode.`lft` between iparent.`lft` and iparent.`rgt` and iparent.`id`=4 /* The category from which to list products */ order by inode.`lft`) as sub where node.`lft` between parent.`lft` and parent.`rgt` and node.`id`=sub.`id` group by sub.`id` order by node.`lft`

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  • Entity framework (1): implement 1 foreign key to multiple tables

    - by Michel
    Hi, i've modeled this: i have an import table, and an import steps table import 1 .. N importsteps Now i have a table importparams, which hold key/value pairs to register all kind of info about the import or the importsteps. So i have modeled a FK in SqlServer which points to the PK of the import table and to the PK of the importsteps table (the ID's for both the import as the importsteps table are guids, so i can query the importparams with either the id from import or from importsteps and get the right importparams). Makes sense a bit? But how can i model this in the EF? I can see it's a bit hard for the EF to model this, because one realtion can point to multiple classes, but is there a way? The workaround normally is just to get all importparams where FK is the ID, but as you know the FK is not available in the EF version 1. I hope you can help me out, michel

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  • NHibernate - does it work well with database-level cascading deletions on foreign key constraints

    - by Nelson LaQuet
    Dose nHibernate play well with database level cascading deletions? What I mean is that if I have a constraint set at the RDBMS level to cascade delete all orphans, will nHibernate invoke any custom delete logic at the application level if I were to delete an entity though nHibernate? Or should I remove the cascading deletions from the RDBMS level and just use the cascading delete feature of nHibernate itself by defining that behavior though its configuration? Thanks

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