I am trying to design a schema where the columns of a table are not fixed. Ex: I have an Employee table where the columns of the table are not fixed and vary (attributes of Employee are not fixed and vary). Frequent addition of a new attribute / column is requirement. Nullable columns in the Employee table itself i.e. no normalization ...
Quantitative Analysts or "Quants" predict the behavior of markets to maximize profits. I am interested in the software that they use to accomplish this. Are there development platforms, libraries, languages or Data Mining suites specifically tailored to Financial Modeling? ...
Hey guys, When writing code I am seeing requirements to change data models (e.g. adding/changing/removing data members from a class). When these data models belong to an interface, it seems difficult to change without breaking the existing client codes. So I am wondering if there is any best practice of designing interfaces/data models ...
I've been wondering how to properly set up many-to-many relationships in ASP.NET MVC 2 using Linq2Sql for quite some time now. I found this blog post that seems to have a similar model layout as mine. If you take a look at the first screenshot showing the data model you can see that each model has "Navigation Properties" at the bottom ...
I have a MySQL DB in which I store data about each user. I would like to add a list of friends for each user. Should I create a table of friends for each user in the DB or is there a better way? ...
This is in mysql, but its a database design issue. If you have a one to many relationship, like a bank customer to bank-accounts, typically you would have the table that records the bank-account information have a foreign key that keeps track of the relationship between account and customer. Now this follows the 3rd normal form thing and...
For Entity Framework associations, are Independent Associations or FK Associations recommended? I have been receiving an error with the multiplicity I tried to use in an independent association. ...
Currently I have several models set up like so, class Account < ActiveRecord::Base has_many :office_hours has_many :staff_positions end class OfficeHour < ActiveRecord::Base belongs_to :account end class StaffPosition < ActiveRecord::Base belongs_to :account end class Document < ActiveRecord::Base end Now I need to set up a...
Is there any program or easy process to take a database and build a model based off Qt around that? ...
What you do before starting the Database model diagram? I mean how you form the Requirements, Specifications etc. Use cases is one thing but anything else? Some best practice or a rule of thumb? Being a self learner I want to see how it goes in the hands of professionals? ...
Let's say I have a simple database with tables 'posts' and 'tags'. Posts can have many tags and tags can belong to many posts. What is the best way to structure the database? I thought of using a list/serialize: tags idx tag_id, str tag_name posts idx post_id, str title, list tag_ids OR having another table with the associations. Pr...
hi guys, i'm doing a system these days, my first one actually and i'm in trouble doing OOAD, i need some help from you all, i'm familiar with diagrams drawn in UML,but when given a scenario i can't make a link, can't see a flow of them, for example now i'm designing the system, i've done use case diagrams and activity diagrams and now i...
I have a small L2S database that was generated with the L2S CreateDatabase command. When I add a class or property to the DBML, the database is not updated automatically. I get errors like "Table not found" at runtime. Is there a way to add new tables and columns to a database? ...
I have a subclass of NSManagedObject (NSMO) called Team. Team has a one to many relationship with another NSMO subclass called Contract. Contract has a 1-to-1 with Player (another NSMO). I would like to simplify my code that uses Team and be able to just refer to its "players". Players will just be an array of players that have a contrac...
Hello, I'm currently rebuilding an admin application and looking for your recommendations for best-practice! Excuse me if I don't have the right terminology, but how should I go about the following? Take the example of "users" - typically we can create a class with properties like 'name', 'username', 'password', etc. and make some meth...
I just want some advice about mysql database. I'm creating a new database for hired cars that need servicing and repairs. I have created 4 tables. Car_id is linked to a primary key table with car information. I was thinking of putting the repair_id and service_id with in the car data table. But that means it will have 3 primary keys in ...
Hello, my question is simple: Is there anyway to generate the database sql creaton script from a Visio 2003 model? I prefer Visio, however can be other program (freeware) that allows me to somehow agilize the process between the model and the sql code. Thanks in advance! ...
I have a user table structured like this: id MEDIUMINT(7), username VARCHAR(15) Would it technically be faster if I changed it to this instead: id MEDIUMINT(5), username VARCHAR(15) I'm confused because even though the total row length in terms of characters and digits would be shorter, I assume the number of bytes used would b...
Hi. In the project where I work I saw this structure in database, and I ask to all of you, what a hell of modeling is this? TableX Columns: isMonday, BeginingHourMonday, EndHourMonday, isTuesday, BeginingHourTuesday, EndHourTuesday and so on... Is this no-sql? I did not asked to the personn who created becaus I'm ashamed :$ Bye. ...
Suppose that we have the following partial ER diagram: Notice that the attachments table will subsequently be used for the messages', submissions', assignments', and lectures' attachments. The problem is with the 3 one-to-one relationships between attachments and messages, submissions, and assignments. According to CakePHP's conventi...