The logical model and/or physical design of a database.

learn more… | top users | synonyms (4)

2
votes
1answer
367 views

Why do/should DBMS cache at the application layer?

This article describes DBMS as caching data at the application layer, which is why they often use Direct IO to bypass the file buffer cache. My question is: what benefits are provided by the DBMS ...
2
votes
1answer
70 views

How to design tables such that a person can work for many companies? [closed]

Database design such that a person can work for many companies?
2
votes
2answers
606 views

SQL order by query results in any arbitrary (but reproducible) manner

For testing purposes I need to get some data from a set of database tables in any arbitrary (but reproducible) order. The idea being that I can later compare two runs using a textual diff tool. Is ...
2
votes
3answers
424 views

Tracking events in a task database

In designing a task database with the usual set of tables (Users, Tasks etc), I'm wondering if there is an accepted way to track changes to fields in the task table? I could just provide a text log ...
2
votes
2answers
71 views

Give every user 3 default 'bookmark' entries

I've got a table users and a table bookmarks. The table bookmarks obviously contains pages the user wants easy access too. But, there's a new requirement now: every user gets 3 unmutable bookmarks. ...
2
votes
1answer
3k views

postgresql bigserial or sequence using jpa

I'm a java developer working with jpa, before to define the indexes in my entities i would like to known which one is faster o better to use?.
2
votes
6answers
6k views

Efficiently storing irregular/repeating intervals (think calendar/events)

I am developing a service that relies on users being able to recieve messages that they themselves choose. These messages need to be stored somewhere before they are send for processing. Right now I'...
2
votes
3answers
9k views

Database design to track student attendance

I was having a doubt regarding the design of a database table to track students' attendance. Currently, my table students have atleast 4000 students. Creating a database for attendance to track their ...
2
votes
1answer
199 views

Is it ok to let users add new columns and tables to your database?

I'm basically making a database of databases. An administrative User can go in and hit "Create Database" (which is basically a table) and set up the column types and how many columns. Other users can ...
2
votes
1answer
2k views

Foreign Keys with Composite Key

Imagine I have a table with the following dependency: (Name, BoughtFrom, TimeBought) --> Cost Where the three attributes in bold form a composite primary key for the table. Now then, I want to ...
2
votes
1answer
183 views

Will a primary key be added as a clustered index?

I've inherited a database where no primary keys were defined on the tables. There are also no clustered indexes assigned to the tables. If I perform an alter table to assign a primary key will this ...
2
votes
2answers
398 views

Database structure for a system with multisite

The system I'm working is structured as below. Given that I'm planning to use Joomla as the base. a(www.a.com),b(www.b.com),c(www.c.com) are search portals which allows user to to search for ...
2
votes
4answers
396 views

Does my table violate normalization rules?

I am developing an emulator for a game. My item table looks like this: -- ---------------------------- -- Table structure for `items` -- ---------------------------- DROP TABLE IF EXISTS `items`; ...
2
votes
2answers
5k views

How would you design a table for a booking system?

I have a design database for a booking system. The booking system requirement are as follows: The booking system allows user to book a time slot (1 hour) between 8 am to 1 pm for Monday to Friday. ...
2
votes
1answer
249 views

New table or new column

Apologies in advance if this is a dumb question. Background: I am a student intern, I've been given the task of adding a new feature the companies client administration system. Basically it involves "...
2
votes
1answer
372 views

Using Foreign Keys in database

I am doing a small application for Invoice.In that the tables will be like this === invoice === id (pk) customer_id (fk) invoice_title invoice_issue_date due_date description created_by updated_by ...
2
votes
3answers
503 views

Express union which is dependent on other results

I would like to make a union of two tables that are actually in a hierarchical constellation. How would I write that in relational algebra? Say table A is the parent of B in a 1:n relationship. ...
2
votes
3answers
2k views

View Design Best Practices

When designing a view, would it be best to retrieve the ID fields where FK relationships exist between the joined tables the desired description field obtained through the FK id relationship both? ...
2
votes
1answer
96 views

Is it dangerous to have duplicated entries in a table?

My table have many duplicated entries, is it dangerous if I don't fix this? My table is structured like this: Music_id | Music_title | Music_author | Music_link 1 Look at me now ...
2
votes
2answers
4k views

database schema for a product with multiple categories and hierarchical categories

I need some opinion on whether I am going in the right direction with this. I am trying to build a e-commerce site (with MySQL backend) where a single product can belong to more one than category ...
2
votes
2answers
391 views

Will this Database design logic work and what should be used?

A few weeks ago I had a client of mine ask me about how complex it would be to develop a custom CRM application similar to the one being provided by highrisehq.com What he essentially wants to do is ...
2
votes
1answer
62 views

SQL Server 2008: how do I hide data from a DB Maintainance User?

Our organisation employs a third party company to do maintenance on our database. To be honest, currently they act as our DBA's since we do not have one. In order to do the maintenance work, they ...
2
votes
1answer
76 views

Alternate Name of Data Dictionary

What is the alternate name of Data Dictionary? ► Index ► Metadata ► Data ► System Catalog What I know already is, data dictionaries store all the various schema and file specifications and their ...
2
votes
1answer
64 views

Is this table in my ERD redundant? (Image)

I am developing a research article database for a project. My professor approved this design but I feel like the Author's_University table is redundant and that University_ID could just be added to ...
2
votes
1answer
139 views

Table to create Ids for one table to many table relationships

I have several tables that will represent an object that can be commented on. I would like to store all the comments in one table. To relate the other tables to the comments, I was thinking of adding ...
2
votes
3answers
241 views

Table naming and Database normalization

I'm creating a database of simulation results, and am trying to do so the right way. I've attempted to show relationships between data to make sure nothing redundant is thrown in. My current ...
2
votes
3answers
537 views

Running Total: To store or compute

Say I have a product table with the following columns: product -------- product_id name And I have another table to record the transaction (IN/OUT) for each product product_transaction ------------...
2
votes
2answers
3k views

Should login id and password be stored in separate table

I am working on my academic project. I have a table for employee records which have employee id, joining date, designation and other fields. I am trying to implement a scheme in which when record of ...
2
votes
1answer
755 views

Foreign Key NULL vs Foreign Key to an empty string

This is a table for a catalog of medicines. Some have a pharmaceutical brand, others are generic (i.e. they will never have brand information) CREATE TABLE medicine ( id serial PRIMARY KEY, ...
2
votes
2answers
256 views

Is unique index better than unique constraint when an index with an operator class is required

Postgres docs say: The use of indexes to enforce unique constraints could be considered an implementation detail that should not be accessed directly. One should, however, be aware that there's ...
2
votes
3answers
446 views

Which design to choose

Suppose I have a website that communicates with a database. In some page of my site i want to exhibit a list with all the students in my database. There are two kinds of students: regular ...
2
votes
1answer
339 views

How to model schedule and keep good constraints?

I have some data that I am having a hard time modeling. Particularly, I am unsure of how I can ensure that I have unique data. This is for a schedule where I am assigning teams to stores. A team will ...
2
votes
2answers
685 views

Best practice database design - user rating tables

I want to create a table to store user ratings of items for collaborative filtering algorithms. So far my table looks like this: IID | UID | Rating i.e. item ID |user id |rating. From ...
2
votes
3answers
815 views

Removing chat history for a particular user from database

I'm currently developing a web chat application using SignleR and SQL server this is my database schema so far I've added an option where the user can Clear Chat history for a particular ...
2
votes
2answers
584 views

What is the advantage of using numeric primary keys in a relational database?

Many tables in a relational database system (in my admittedly limited experience) have this sort of structure (Oracle syntax as that's what I'm used to): create table widgets ( widget_id number ...
2
votes
1answer
335 views

Clustered composite key high fragmentation and fill factor

I've recently made a table to hold the language preferences of my users as follow: CREATE TABLE [dbo].[systemUserLangPreference]( [systemUserID] [int] NOT NULL, [langID] [int] NOT NULL, [...
2
votes
2answers
268 views

Relations between a imeid, sim chip, and account from a cellphone company?

I've never really had a cellphone (that I owned the account to...long story), but at work we have them, and we want to get a series of relations between accounts, devices (mifi's, tablets, cellphones),...
2
votes
1answer
368 views

What's better here - a single column or multicolumn primary key?

Let's assume you have a table groups and a table item. Each item belongs to exactly one group. It is an inherent part of that group. An item cannot exist outside of a group and it cannot be moved to ...
2
votes
1answer
232 views

MS Access + SQL Server for 1160 users - Is it worth it? (Please Help!) [closed]

Our school in Delhi (India) wants to develop a professional and robust in-house database (SIS) that should handle vast amount of student information, including admissions, registration, re-enrollment, ...
2
votes
2answers
379 views

Performance effect of indexing foreign keys

My database is for an HR application with performance reviews and I am interested in whether I should index my foreign key. There are two tables involved. The first is a ratings table with 2 columns: ...
2
votes
1answer
598 views

Table for optional parent/child relationship

Assuming we have the following table: Item, Parent, Child and Parent is the parent of child. The item can either belong to a parent or child and not both. I have other tables that are similar to ...
2
votes
1answer
908 views

Best practice around sys.dm_db_missing_index_group_stats in SQL Server

I have a fairly simple query using sys.dm_db_missing_index_group_stats that identifies missing indexes in my SQL Server database. This is pretty commonly used. My question is how do I identify which ...
2
votes
2answers
621 views

Relational database for address model

I want to design an "Address" model for all types of entities like users, businesses, etc. I have two types of main models: one is User and the other is Business. Each one has different address types ...
2
votes
1answer
135 views

Is there any reason that metadata should not be a part of my database schema?

By metadata I mean things such as: the owner of an entity permissions associated with an entity the date and time of data entry the surety of entered data the format of a text attribute descriptive ...
2
votes
1answer
168 views

Databases design decision - Mobile & Web

This may be a question a little broad but... I'm currently having the following dilemma: Having a web application (already deployed) and a new mobile app, I'm currently working on the mobile app ...
2
votes
2answers
1k views

Closed loops in database model, does it affect the performance?

I have heard that having loops in the database relational model should be avoided. From what I can think of, it is not a good practice, because there will be more than one different pathes to get the ...
2
votes
1answer
1k views

How to set unique columns combination

see this table: CREATE TABLE IF NOT EXISTS `default_messages_users` ( `id` int(11) NOT NULL AUTO_INCREMENT, `message_id` int(11) NOT NULL, `owner_user_id` int(11) NOT NULL, `to_user_id` ...
2
votes
3answers
241 views

is id and phone number enough to uniquely identify a row in phone numbers

Was designing a table a customer_phone_numbers table a while back, which only purpose was to allow us to store as many phone numbers as a user wanted to have on file. I originally came to the ...
2
votes
2answers
923 views

mysql products db design

I am building a products site with php and mysql(no shopping cart). I have 400k products, the main site with 2 methods for query. query for products types, all the query by menu, cloud tags (no ...
2
votes
2answers
2k views

Joining based on date (or date range)

I'm not sure if I've completely fudged the design of my small hobby database (I'm not a DBA by any means), but I have a table like this (primary key is (staffid, effectivefrom)): staffid | target | ...