data-modeling

I'm building a group calendar application that needs to support recurring events, but all the solutions I've come up with to handle these events seem like a hack. I can limit how far ahead one can look, and then generate all the events at once. Or I can store the events as repeating and dynamically display them when one looks ahead on the calendar, but I'll have to convert them to a normal event if someone wants to change the details on a particular instance of the event. I'm sure there's a better way to do this, but I haven't found it yet. What's the best way to model recurring events, where

Which one is the best practice and Why ? a) Type Table, Surrogate/Artificial Key Foreign key is from user.type to type.id : b) Type Table, Natural Key Foreign key is from user.type to type.typeName : I believe that in practice, using a natural key is rarely the best option. I would probably go for the surrogate key approach as in your first example. The following are the main disadvantages of the natural key approach: You might have an incorrect type name, or you may simply want to rename the type. To edit it, you would have to update all the tables that would be using it as a foreign key. An

Say I had some data, for which I want to fit a parametrized model over it. My goal is to find the best value for this model parameter. I'm doing model selection using a AIC / BIC / MDL type of criterion which rewards models with low error but also penalizes models with high complexity (we're seeking the simplest yet most convincing explanation for this data so to speak, a la Occam's razor ). Following the above, this is an example of the sort of things I get for three different criteria (two are to be minimized, and one to be maximized): Visually you can easily see the elbow shape and you

The database I'm designing has 3 major tables: BOOKS , ARTICLES , NOTES . Each book or article can have multiple notes, my original design was just like that, which means both notes on books and notes on articles go the 'notes' table. Here are the columns for the NOTES table: note_id note_type note_type_id note_content NOTE_TYPE can be either 'book' or 'article'; NOTE_TYPE_ID is the FK for a book_id if the note_type is 'book' OR an article id if the note_type is 'article'. Now I start to wonder if that's the correct(or best normalized) design. An alternative approach is to use 5 tables books /

Choosing good primary keys, candidate keys and the foreign keys that use them is a vitally important database design task -- as much art as science. The design task has very specific design criteria. What are the criteria? The criteria for consideration of a primary key are: Uniqueness Irreducibility (no subset of the key uniquely identifies a row in the table) Simplicity (so that relational representation & manipulation can be simpler) Stability (should not be altered frequently) Familiarity (meaningful to the user) What is a Primary Key? The primary key is something that uniquely identifies

I have a document "user" which has a key called "photos". Here is an array of strings being saved, namely the IDs of the "photo" documents. I want to query "user" by this "photos" field: I want all users who have this ID in the "photos" property. Is this possible through firestore? Added 'array-contains' query operator for use with .where() to find documents where an array field contains a specific element. https://firebase.google.com/support/release-notes/js 5.3.0 Update : also available in @google-cloud/firestore : https://github.com/googleapis/nodejs-firestore/releases/tag/v0.16.0 Update 2

I was wondering if you have a website with a dozen different types of listings (Shops, Restaurants, Clubs, Hotels, Events) that require different fields, is there a benefit of creating a table with columns defined like so Example Shop: shop_id | name | X | Y | city | district | area | metro | station | address | phone | email | website | opening_hours Or a more abstract approach similar to this: object_id | name --------------- 1 | Messy Joe's 2 | Bate's Motel type_id | name --------------- 1 | hotel 2 | restaurant object_id | type_id --------------- 1 | 2 2 | 1 field_id | name | field_type --