Model a Zero or One to Many Relationship

Posted by John on Stack Overflow See other posts from Stack Overflow or by John
Published on 2010-03-27T17:27:23Z Indexed on 2010/03/27 17:33 UTC
Read the original article Hit count: 272

Filed under:

data-modeling

|

database-design

How should I model a zero or one to a many relationship in the database? For example, a user record may or may not have a parent. So should my user table have a t_user.parent_id or should I have an associative table called t_user_hierarchy with the columns t_user_hierarchy.parent_id and t_user_hierarchy.user_id?

© Stack Overflow or respective owner

Related posts about data-modeling

Handling incremental Data Modeling Changes in Functional Programming

as seen on Stack Overflow - Search for 'Stack Overflow'
Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code… >>> More
Data Modeling Resources

as seen on SQL Blog - Search for 'SQL Blog'
You can find many different data modeling resources. It is impossible to list all of them. I selected only the most valuable ones for me, and, of course, the ones I contributed to. Books Chris J. Date: An Introduction to Database Systems – IMO a “must” to understand the relational model… >>> More
Struggling with a data modeling problem

as seen on Stack Overflow - Search for 'Stack Overflow'
I am struggling with a data model (I use MySQL for the database). I am uneasy about what I have come up with. If someone could suggest a better approach, or point me to some reference matter I would appreciate it. The data would have organizations of many types. I am trying to do a 3 level classification… >>> More
Need some advice on Core Data modeling strategy

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm working on an iPhone app and need a little advice on modeling the Core Data schema. My idea is a utility that allows the user to speed-dial their contacts using user-created rules based on the time of day. In other words, I would tell the app that my wife is commuting from 6am to 7am, at work… >>> More
Data Modeling of Entity with Attributes

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm storing some very basic information "data sources" coming into my application. These data sources can be in the form of a document (e.g. PDF, etc.), audio (e.g. MP3, etc.) or video (e.g. AVI, etc.). Say, for example, I am only interested in the filename of the data source. Thus, I have the following… >>> More

Related posts about database-design

(Database Design - products attributes): What is better option for product attribute database design

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I new in database design. What is better option for product attribute database design for cms?(Please suggest other options also). option 1: 1 table products{ id product_name color price attribute_name1 attribute_value1 attribute_name2 attribute_value2 attribute_name3 attribute_value3 } option… >>> More
Book Review: Pro SQL Server 2008 Relational Database Design and Implementation

as seen on SQL Blog - Search for 'SQL Blog'
Investing in proper database design is a very efficient way to cut maintenance costs. If we expect a system to last, we need to make sure it has a good solid foundation - high quality database design. Surely we can and sometimes do cut corners and save on database design to get things done faster… >>> More
Advice on database design / SQL for retrieving data with chronological order

as seen on Stack Overflow - Search for 'Stack Overflow'
I am creating a database that will help keep track of which employees have been on a certain training course. I would like to get some guidance on the best way to design the database. Specifically, each employee must attend the training course each year and my database needs to keep a history of… >>> More
Fiscal year handling strategies in database design

as seen on Stack Overflow - Search for 'Stack Overflow'
By fiscal year I mean all the data in the database (in all tables) that occurred in the particular year. Lets say that we are building an application that allows user to choose from different years. What way of implementing this would you prefer, and why: Separate fiscal year data based on multiple… >>> More
Database design for summarized data

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a new table I'm going to add to a bunch of other summarized data, basically to take some of the load off by calculating weekly avgs. My question is whether I would be better off with one model over the other. One model with days of the week as a column with an additional column for price… >>> More