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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Product Attribute System While Avoiding EAV

I'm working on building an attribute system for products. The issue that I'm running into is that various products can have very different attribute requirements. Some E-commerce websites such as ...
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27 views

Normalization to 2NF and 3NF

I solved this example to determine 2NF and 3NF. I would like to check if my answer is correct. Can somebody check the 2NF and 3NF of this example, please? R( A B C D E F G H I J) with functional ...
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Loose database structure

I'm just thinking out loud. I'm wondering if there's any database technology where it's structure does not need to define upfront? For example it may start off with just one column or roll and user ...
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25 views

Soccer league ER diagram

I am planning on creating a database to track teams and players in a soccer league. The stats I wish to track are as follows... goals scored/conceeded(gk), assists, minutes played, cards received and ...
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11 views

Will coloum size change when trying to use single unicode character in place of multiple ASCII characters?

I have a column in utf8_unicode_ci collation for text type in MySQL. The content is in Unicode, I have used tags like {br}, {v}, {t}, {h} etc.., throught the database. I am now thinking of changing ...
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19 views

Alternative to RDBMS: Modeling Exam/Testing data

I'm a born and bred relational database guy and C# programmer dude. IBM DB2 & VB.Net in school. TSQL & C# at work. I'm planning a project for fun: Designing a Testing platform that goes from ...
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97 views

Reviewing relational database tables

I am building a database, but I am a little bit confused with my table relationships. I wish someone could help review my table relationships below for me and tell me where I am going wrong. I have ...
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290 views

Time series and gap filling

I have to choose a database server for storing big time series data. Currently I use PostgreSQL, but I've found that Vertica supports automatic gap filling for missing data and that's really nice. ...
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29 views

How to enforce an “exactly-one-per-group” constraint?

I have a table x that I've defined like this: CREATE TABLE x ( xid INTEGER NOT NULL PRIMARY KEY, yid INTEGER NOT NULL REFERENCES y(yid), is_principal BOOLEAN NOT NULL ); This definition ...
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How to query against legacy data that needs to be cleaned up?

I have an existing SQL Server DB with 3 tables (note: this is a made up example, but modelled after a real problem). Artists : contains music artists MusicRecords : contains information on music ...
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23 views

Copy of a database with an existing database with schema and data in sql server

I have two databases one is having master kind of tables and other will have transaction data. I should create a new database with a structure of an existing database to my clients. Here is the ...
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2answers
17 views

How to normalize a table that contains a CK not included in the PK?

I have the following table. The PK is model_ID. Assuming that the modelName field is unique(that is, no two brands can have an identical modelName), there is a transitive dependency between modelName ...
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24 views

Advisable number of foreign keys in a single table [on hold]

I was wondering, keeping performance and optimizations in mind, while designing the database, is there any advisable number of foreign keys you should keep in a single table? At present, few of my ...
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Normalising shared entities and applying constraints

I'm looking for a specific "best practice" or "pattern" concerning entities that are shared between different entities, having a relation to one of many. For example, one may have the generic entity ...
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17k views

Add a new Column and define its position in a table

I have Table A with 5 columns: TableA -- Name Tel Email Address I want to add a new column (mobile) in between Tel & Email: TableA -- Name Tel Mobile Email Address If I use ALTER TABLE ...
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42 views

If A and B are candidate keys, then AB is candidate key or not ?

If R{abc} is a relation, f{ a->b b->a a->c b->c }, then a and b are candidate keys. What about ab ? Is it a candidate key or is it a super key or both ?
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What kind of data cannot be stored economically in a database / data-warehouse?

Someone mentioned this in a presentation but didn't provide any examples. This stuck with me and I am trying to figure out what kind of data couldn't be stored economically in datbases ever since. It ...
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14 views

How to model role and different activities

I am new in the database design and I'm facing this problem, I hope somebody can help me. In my domain we have 3 roles, Non-Supervisor, Supervisor, Manager. I created a Person table and a role table ...
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Is there a way I can speed up queries against this particular view?

I have three tables in a PostgreSQL database that I'm querying via a view and some joins. CREATE TABLE network_info ( network CIDR NOT NULL, some_info TEXT NULL, ...
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Manage orders based off product attributes and quantity

I'm developing a database for an online store in which the Products have multiple attributes and attribute types. ATRIBUTES TYPES atrtype_id name (like size, color...) ATRIBUTES atribute_id ...
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60 views

What is the best design for storing courses subscription data?

Building an app that will manage lessons, students, courses. Each lesson belongs to a certain course. A student can subscribe to a single lesson or to a whole course. So it seems straightforward that ...
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15 views

linking a single table (comment) to multiple tables (article,link,attachment)?

the main idea is that i can post an article , link or an attachment and i can receive comments on each of these types of posts (the structure of the comment is the same) , the problem here is that i ...
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92 views

representation in ms-access

I have a database in microsoft access. I want to know how to look up a singular datum from a reference table giving a dynamic set of values. Here is a representation of what I mean: I have the ...
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Multiple user roles with different attributes

I need to design a database that has multiple users, with multiple roles. For instance, a user can be an admin, company, employee, or customer. Each user can have any number of these roles. Right now ...
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130 views

Proper implementation of child (derived) table PK/FK during single and multiple inheritance hard coded generalization physical data model

Below is an image of hard coded generalization UML logical model of entities. I'd like to implement these classes as tables in a physical data model. Two derived classes/entities (Class2 and ...
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what databases have the implementation of sort merge join? [closed]

So many databases and distributed data warehouse frameworks, which have the sort merge join implementation?
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How to store likes to posts in Parse.com database?

In my parse database I have a classed called Post and Like. Should I create a field likes in Post class with Relation<Like> type or there is another better option of storing likes in Parse DB?
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68 views

Database structure for product attributes on orders

I'm making a POS and currently kind of stuck on the order proccess due to the product attributes. As of now the DB looks something like this: tbl_products tbl_attributes (attr id, name, extra ...
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39 views

Compare the structure of two MySQL Databases

I have two MySQL databases that are very similar to each other. How can I find out the differences in tables, and the differences in columns in each table? the databases are in different schema. ...
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1answer
705 views

Designing a reservation system schema

I am not sure if this has been asked before, however I am tasked with designing a new reservation system for my organization We have an older system which simply stored the booking in a table, and it ...
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599 views

Database table design question

Firstly, database novice here. I'm trying to create a system for processing Sales Orders into Purchase Orders and then split the Purchase Order into Shipping Containers. The systems needs to be able ...
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25 views

How to cast as type of a table column?

I have multiple views with union like this: select column1, column2 from mytable union select cast(extcol as nvarchar2(15)), cast(extcol2 as nvarchar2(10)) from exttable But later I change the size ...
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37 views

MySQL Dynamic columns duplicate value workaround

As the title suggests i have the following code which transposes certain row values into field names, however the problem im having is that the values "closed" & "reopened" may appear in several ...
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3answers
450 views

Rent weekly cost database design

I have a database which contains a table BUILDING with in each row details about some building, another table BUILDING_UNIT contains rows with details about a single building unit which refers with a ...
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Database design for varying prices from multiple vendors

I am designing a database where the products are sold in bulk with multiple pricing options, from 4 different vendors. What is the best table configuration to store this information? Id like to be ...
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890 views

Designing a database for a site that stores content from multiple services?

I'm building a site that implements David Allen's Getting Things Done that pulls in your email, Facebook newsfeed, tweets from those you follow on Twitter, and more services are planned. The problem ...
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145 views

Duplicate Relationships in Rails/MySQL Healthcare Application

Overview of the Application I am building a Ruby on Rails application to organize medications, using MySQL. The goal of this application is to provide dosage specific treatment recommendations, and ...
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15 views

Trying to Figure out an ER Diagram for a set of instructions

Below is information about a database and I want to come up with the ER Model. (Im not sure if this is the right place to post this. Im new to this page) professors have an SSN, and a name projects ...
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1answer
23 views

Using part of a compound key as foreign key

We have the following situation, in which we have three tables: Article ------- - Id (PK) - Supplier_Id - Supplier_Contactperson_Id - Name Supplier --------- - Id (PK) - Name SupplierContactperson ...
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1answer
361 views

Removing “duplicates” within a time range

I have a table that contains number plate data with a date and time stamp, collected by a plate-reading CCTV camera at a site entrance. Vehicles stopping at the site entrance will create multiple ...
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41 views

Database design for attendance feature

My app has a requirement wherin we need to capture attendance details of a class. A class typically has 50-60 students and there will be records with attendance/absense status of each student for a ...
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20 views

What should be the structure for a person-to-person store database

I am going to create a person-to-person store with Laravel, a website whose users can share and sell their product or their mobile, TV, Computer, Shoes, Shirts, Books ,Cars, Bags, Animal etc. I am ...
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Performance/Maintenance Implications of a Write Heavy Table In An Otherwise Normal “CRUD” Database

We have a small-ish (<100,000 rows) MySQL database (on Amazon RDS). Its supporting a fairly simple read heavy CRUD web application. Currently we're building out a web analytics system. It will ...
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96 views

Text Storage and Database Design Optimization in a SQL Server Database

Given a database with a number of columns (c), where some of these columns contain text that is one of multiple values due to a set CONSTRAINT on the columns, what is the most efficient way to ...
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32 views

mongo: how should I layout my data

I have 2TB of data currently spread across many CSV files that looks like: { 'rec_date': "2010-01-29", 'rec_time': "09:15:00", 'site_no': '46', 'data_owner': '1', 'flow_period': '5', ...
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58 views

Transpose MySQL rows as column names - DYNAMIC

My goal is to be able to calculate the time difference between the ticket timestamp being created and closed and if reopened Add time from being reopened to closed again etc.. I have an existing mySQL ...
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60 views

Covering Index - Insert Performance

We are running some performance tuning on our database in SQL Server. The database in itself is pretty small with around 13 tables. But there are multi-level relationships between tables. When I try ...
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1answer
25 views

Daisy chaining two is-a relationships?

I'm currently dabbling in ER modeling and wondering if it is possible to create a chain of is-a relationships. Example: Here I'm basically trying to model specific in-stock items available for rent ...
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Database systems with users and sub users accessing the data

I am making a database for school student maintenance. Below is the basic description. There are schools. One school has many staff (i.e: Principles,Teachers, Section Head, Office Staff etc) These ...
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478 views

How to normalize my db schema for a quiz application?

I am putting together a quiz application. (I'm calling each quiz a "challenge") I have a "challenge" table and a "challenge_question" table which is pretty straightforward. challenge table: id ...