As the question title, is there a way to do this? eg: DrivingLicence --------------- CanDriveCar (bool) CanDriveMotorbike (bool) CanDriveBus (bool) You can't drive a bus without a car licence, so I want the DB to throw an exception if anyone tries to give someone a bus licence when they haven't a car licence. ...
How the memory is allocated,reallocated and autoextended while creating tablespaces?what is meant by initial and default in tablespaces and how the next is a multiple of five times DB_BLOCK_SIZE? ...
Maybe i'm going about this wrong but my working on a database design for one of my projects. I have an entity with a classification column which groups up entities into convenient categories for the user. These classifications are predefined and unchangeable by the user (at least thats the current design). I'm trying to decide if I sh...
Links have one or more tags, so at first it might seem natural to embed the tags: link = { title: 'How would you implement these queries efficiently in MongoDB?' url: 'http://stackoverflow.com/questions/3720972' tags: ['ruby', 'mongodb', 'database-schema', 'database-design', 'nosql']} How would these queries be imple...
In our application, we support user-written plugins. Those plugins generate data of various types (int, float, str, or datetime), and those data are labeled with bunches of meta-data (user, current directory, etc.) as well as three free-text fields (MetricName, Var1, Var2) . Now we have several years of this data, and I'm trying to des...
Should I clone the entire product along with all related data into another table for posterity, effectively logging the current state of the product, as it was when the user purchased it? Pros: The product (as the user saw it when it was purchased) is held for posterity and never changed. If the product data changes over time, it won...
What is the best way to re-use reports on different tables / datasets? I have a number of reports built in BIRT, which get their data from a flat (un-normalized) MySQL table, the data which in turn has been imported from an excel sheet. In BIRT, I've constructed my query like this, such that I can change the field names and re-use the ...
I have the following mysql table schema: SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO"; -- -- Database: `network` -- -- -------------------------------------------------------- -- -- Table structure for table `contexts` -- CREATE TABLE IF NOT EXISTS `contexts` ( `id` int(11) NOT NULL AUTO_INCREMENT, `keyword` varchar(255) NOT NULL, PRI...
In Django, I have the following models: class Pink(models.Model): ... class White(models.Model): ... pinks = models.ManyToManyField(Pink) ... At some point, I needed to define an ordering of Pinks inside a White (in order to have White1.pinks: P1, P2, P3 instead of a random White1.pinks: P2, P3, P1), so I've created ...
Hi, I am making a db schema for facebook like wall structure. I need to save wall posts, share a link, share a video stuff into my database. Till now I am able to make this schema : GO CREATE TABLE [Wall] ( [ID] [int] NOT NULL IDENTITY(1, 1) , [PostText] [nvarchar](MAX) [PostedByUserID] [int] NULL , [PostedO...
i has 3 plans: 1, in questions table: question ------------------------------------ id title content ... tags ------------------------------------ 1 aaa bbb ... tag1,tag2,tag3 (use , to split more tags) 2, in tags table and split: tags ------------------------------------ id tag --------------------------...
I am writing some code to find duplicate customer details in a database. I'll be using Levenshtein distance. However, I am not sure how to store the relationships. I use databases all the time but have never come accross this situation and wondered if someone could point me in the right direction. What confuses me is how to store the...
Hello. Rightly or wrongly I’m dealing with a generalised SuperType table which I have the sub type data for but not the SuperType data. However to insert the SubType data I obviously need the Identity ID from the SuperType table first. I was wondering if anyone else has come across this and how they got around it. Unfortunately there...
Can we apply two primary keys in a table in anyway? ...
Hello, which is the best primary key to store website address and page URLs? To avoid the use of autoincremental id (which is not really tied to the data), I designed the schema with the use of a SHA1 signature of the URL as primary key. This approach is useful in many ways: for example I don't need to read the last_id from the databa...
In my previous question a lot of users wanted me to give some more data to toy with. So I got working on exporting all my data and processing it with Python, but then I realized: where do I leave all this data? Well I decided the best thing would be to stick them in a database, so at least I don't have to parse the raw files every time...
At my job, we have judges perform a variety of tasks, e.g., rate movies or compare two pieces of text. We're in the process of designing a new database to hold all our data (we have some data already, but the database it's in is pretty hack), and I'm starting to build a Rails analytics application that will serve as a dashboard on these...
I have a fact table called Loans. In this table in a loan identifier, the date the loan was made, and the amount of the loan. The business requirement I don't quite know how to do in the datawarehouse is the following. The loan amount can be adjusted in the future. So lets say August 1st we make a loan with an id of 1 and a amount ...
Vendor (PK) - Id Name Stand (PK) - Id VendorId - fk - cascaded delete if Vendor is deleted) Name Item (PK) - Id VendorId - (fk - cascaded delete if Vendor is deleted) Name Price UnavailableItem (PK) - ItemId - (fk - cascaded delete if Item is deleted) (PK) - StandId - (fk - cascaded delete if Stand is deleted) The database above repr...
I'm working on a social network. From what I've gathered, there's a limit at 1792 for number of tables in a mysql cluster. I will probably end up with 100-200 tables for now. Is this reasonable/acceptable? Or is my db schema horrible like this? What is reasonable for a large scale project such as a social network? Also, what then is t...