Database design is the process of specifying the logical and/or physical parts of a database. The goal of database design is to make a representation of some "universe of discourse" - the types of facts, business rules and other requirements that the database is intended to model.

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Mysql error while creating FK

here is structure of both tables category table CREATE TABLE category ( `catID` bigint(20) NOT NULL AUTO_INCREMENT, `title` varchar(60) NOT NULL, `created_at` timestamp NOT NULL DEFAULT ...
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239 views

What are the pros and cons of this schema for flashcards app?

I am planning a flashcards app with the following schema: user(id, name, email) flashcard_group(id, user_id, group_name, group_tag) flashcard(id, group_id, question, solution) guess(id, user_id, ...
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1answer
125 views

Is MySQL replication suitable for a Write Mostly application?

I'm considering adding another server to my one-server setup application with 600GB MySQL DB. The db and the apache are both running from the same server. In order to avoid backup downtime and improve ...
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559 views

MySQL database normalization 3NF

I have homework where I need to create simple web interface and a DB normalized to 3NF. I've chosen ISP client selfcare as my database purpose. Web interface is no problem, the normalized DB is. After ...
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125 views

Unique foreign key constraint between three tables

I'd like to track appointment attendances. Visitors can have appointments, or they can just turn up. If they have an appointment, and miss it, in which case I'd like to record a reason for the missed ...
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408 views

Should I Link a Fact to Hierarchical Dimension at ALL Levels or only the most granular?

Related question about the same project here. I'm looking at two approaches to model a hierarchical relationship between my fact and dimension tables in a data warehouse for storing IT infrastructure ...
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1answer
214 views

Representation of circular references constraint

We have a database where we store commands and properties for devices that may be controlled via a network. For instance, "Concrete Device" is an instance of some DeviceType, which in turn contains ...
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204 views

Mobile Phone & Tariffs

I have designed database tables of Mobile Phones & Tariffs. It should support multiple mobile networks, sale type and the related affiliate. Points (for operators) are vary depending on the ...
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497 views

How do I optimize this database design?

I need to create a vehicle tracking database. There are several vehicles that send data, consisting of around 20 parameters, to my database. The parameters of a vehicle include the constants ...
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1answer
137 views

Database column vs row size

I have Column A and Column B in a single table. I need to add 1,000,000 records to this table. I have 2 options: Keep 2 columns and add 1,000,000 records Add more columns and flatten out the ...
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4answers
605 views

Can this business logic be enforced by a conditional database constraint?

I am trying to duplicate the business logic embodied an intranet C# web application in the database so that other databases can access it and work under the same rules. This "rule" seems difficult to ...
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1answer
443 views

Curious Database building Problem (ER Diagram)

I am trying to build an EER Model for a Autostore that has 5 locations and offers a range of auto products. They offer car repairs and roadworthy tests as a service also. I need to be able to make ...
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1answer
81 views

linking databases for reporting

I am attempting to design a simple reporting feature for some financial market data. I have a few sets of data, and I am trying to figure out what will be the best way to organize the tables, in ...
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2k views

ER Modeling; multiplicity basics - one to many or many to many?

Apologies for a basic question, but I’m having difficulties determining the multiplicity constraints for a database I’m trying to design. Our team undertakes a number of services/projects...each ...
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361 views

An “unlimited” data model

I need to store an unknown amount of fields. Some are numbers (like IDs, zip codes and times), some are short strings (like names and states), and some are longer strings (such as descriptions). All ...
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2answers
473 views

Replacing composite key with surrogate

I have the following table that has a couple of million rows in it and is 99% fragmented virtually all of the time. My plan was to insert a IDENTITY field as a surrogate key to replace the current ...
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2answers
178 views

Web Database - How to store user information

I'm starting to design a database to use in a web solution and would like to understand if there is any benefit to storing passwords (and the rest of the user information for that matter) in a ...
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1answer
406 views

Surrogate key / Primary key: Better to use an existing unique data field or create a key field?

I am not sure if this question has been asked or not. At least I couldn't find it. I am curious about a primary key in terms of efficiency with data searching and retrieval. This is a hypothetical ...
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1answer
2k views

MYSQL Social Networking website - Database Design, Data Growth and Hardware

Introduction I have a system around one million users (community based). It has around 6000 groups (fixed , no change). But there is no discussion board for these groups yet. Building discussion ...
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SQL Server - Database per company. How to query across databases?

We are designing a product that, as per the client's request, must utilize a database-per-company design approach with one shared database holding common data. We are using SQL Server 2012 for the ...
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1answer
2k views

Why is a Star Schema more normalized than a 3NF Schema?

According to Oracle's documentation, third normal form schemas "may require less data-transformation than more normalized schemas such as star schemas". I'm confused, I thought 3NF is the most ...
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225 views

Can graph databases be easily distributed?

I have never worked with graph databases such as neo4j, I would like to know if they support easily replication and clustered distribution as well as key-values databases, or if there inherent ...
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1answer
1k views

Modelling Relationships in an E-R Diagram, Table or Foreign Key?

Should a relationship in an E-R diagram be created in the database as a table or a foreign key? For example: a tutor lectures a class I see it as three possibilities: there is a "lectures" ...
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4answers
486 views

How do I develop this data model without a circular reference?

I am trying to develop a concept for a new call tracking system for a help desk. The top 3 levels reference each other. I am trying to determine a better way to link these tables, and am drawing a ...
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1answer
97 views

How do you manage a list for particular object. for eg. user comments on specific object(user post etc.)

I am new to database and web application development. I want to know how to store a list for a particular object in a database. For example, user comments for a particular post(object), or the ...
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1answer
1k views

Database Design for Questions and Answers

I'm building a website that will host a variety of questionnaires. Each questionnaire has a different number of questions and each question has a different number of answers. I have attempted to ...
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1answer
2k views

How to design a table for storing news items?

I have a script that can get result from news websites and it will run every hour. The php script will get the title and content. The things I want to store in MySQL are: title content ...
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520 views

What should I use? A string or 15 integer fields?

I am developing a student tracking program where I need to store 15 exam marks. I can store the marks as a string and split them up when I need to, for purposes such as performing arithmetical ...
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1answer
233 views

From a design perspective, what is the difference between an inventory system and an asset tracking system?

From what I can see, the database design is similar. One is the consumables that are resident in a warehouse (inventory). The others are items, capital, that are assigned to people or places, but ...
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792 views

Modelling constraints on subset aggregates?

This is a cross-post from Stack Overflow. I figured I might get more interesting thoughts here. I am using PostgreSQL but I figure most of the top-end db's must have some similar capabilities, and ...
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1answer
1k views

EAV structure explained in Layman's terms

I've read several articles online that explain how EAV structures work, but there are different interpretations of them. Some articles mention that it's a representation of a data model metadata (or ...
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1answer
258 views

Compare MongoDB and MySQL

Can anyone help me to make right decision for choosing scalable and reliable database? I have to create 3-4 tables with around 200 columns each and these tables will have around 5000 data records. As ...
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3answers
297 views

Database design for changing number of fields

Google Contacts lets you to enter more than one phone number, or email address for a contact. You can add as many as you want. I don't know if there is a limit, other than practical list size. To ...
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2answers
474 views

Many to Many Relationship Question

I have a database, with one main table: Project, and about 10 other tables (Entity1, Entity2, etc.) Each of the different entities can belong to one or many projects. I know I can have tables like ...
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243 views

Improving database design for category based site

I'm working on a site that gets about 30k visits a day and it makes use of a lot of queries which uses UNION's over about 45 different tables, these tables generally range from about 15k rows to about ...
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1answer
226 views

How to simplify schema for multi database / hundreds of millions of rows data set

We currently have a MySQL data set that was started about 10 years ago that aggregates a log of data, and accumulates millions of rows each month. The people that developed our system started ...
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421 views

Data Compression Through Base36 Encoding

I'm trying to store a lot of large numbers that truncate when stored as INT values. Unfortunately they are too large for this type. I'm thinking about using Base36 encoding to accomplish this. Are ...
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1answer
2k views

Proper tuning for 30GB InnoDB table on server with 48GB RAM

I have a 30GB 15M rows InnoDB MySQL 5.5.15 table. It is running on a server with many other MyISAM tables (300GB db). The system has 48GB RAM. Besides the default configurations, I've changed the ...
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2answers
926 views

Vehicle spare parts inventory datadase model

I am modeling a database to be used for vehicle spare parts inventory management and I am stuck... Some spare parts can be broken down from a kit into component parts. I would like to create a model ...
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1answer
354 views

MySQL table locks solution -> InnoDb / Partitions

I'm experiencing many table locks in a MyISAM MySQL table that is pretty big (Constx10xGB and 15M rows). It's mainly caused due many heavy inserts. My current thoughts to optimize: Changing to ...
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1answer
344 views

MySQL table locks solution -> InnoDb / Partitions

I'm experiencing many table locks in a MyISAM MySQL table that is pretty big (Constx10xGB and 15M rows). It's mainly caused due many heavy inserts. My current thoughts to optimize: Changing to ...
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1answer
292 views

Database for an application similar to Chatroulette

I am making an app that is similar to Chatroulette. When a user starts the app it finds someone that is not currently talking to anyone and have them talk to each other. At any point a user could ...
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4answers
7k views

What's better/faster? MySql or FileSystem?

Let's imagine a web site that is a directory of people. For each person there may be a profile photo and a biography. I'll admit my SQL queries could be better but in general what would be faster and ...
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1answer
294 views

Schema for 1 <-> 0..1(+), many related but only one primary

Using tools available in SQL Server 2008 and Entity Framework, what is a solid way to represent a one-to-many relationship, where there is an underlying unique relation that I need to enforce? My ...
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1answer
303 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` ...
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2answers
832 views

Database design experienced view

I want to make a database that stores countries, their respective states, and cities. I am confused how to normalize these. Can anyone help? My ideas: Table 1 Countries (id pk, name , code) ...
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1answer
170 views

How can i prevent decryption in SQL Server procedures

I came across in internet tool to decrypt procedures, I checked my database with this tool to decrypt my procedures and it works fine, now the problem is I wish to prevent this kind of tools from ...
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1answer
2k views

How do I perform a UNION query on a dynamic list of tables?

My database has an unknown amount of tables, named with the same prefix followed by a random string: _ct_<random_string>. Each of these tables has the same data structure. I also have another ...
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4answers
1k views

Reason to not use nullable number in Oracle?

Our company is interfacing with another software company for a joint project, and we were told that, if a particular value should not be displayed, we should pass in a -5000 (their arbitrary sentinel ...
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2answers
1k views

How can I save a severely fragmented database/table?

I've recently made a discovery that might explain my slow SQL run times. I found out that the default in SSMS is to allow mdf growth of 1MB at a time. When the size of one table alone is roughly 23 ...