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

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What table should I host data linking two objects from separate tables?

I've tried searching around, but I'm not too sure how to correctly formulate this question, and found nothing. Could be a duplicate. What is the best way (most efficient way) to host data that will ...
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0answers
552 views

Postgresql - How to Convert all Column Names to Lowercase

I have a travel survey with a series of tables (lots and lots of columns) that I exported from MS Access into a postgres database. I've search around a lot for an explanation of how to convert all the ...
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2answers
82 views

compound primary key with separate id field for reference

I am trying to build locations into a database like so: Country -> Region -> Town Countries will be populated with a list of pre-defined worldwide countries, regions & towns are input by users. ...
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1answer
2k views

Slow delete caused by many foreign keys

My DB has about 90 tables. Most of the tables have an UpdatedBy and AddedBy column that have foreign keys pointing back to the user table. With even moderate amounts of data spread throughout the ...
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0answers
52 views

Database for temporary data with 2^20 variables [closed]

I'm building a site to display graphs based on a data set with 1024^2 different variables (columns, traditionally) per point (record). That is to say, the points are in 1048576-space. The data is ...
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1answer
62 views

Delete and Update of Foreign keys [closed]

I'm working on a school project. And I'm required to implement it using Java-EE and SQL Server. I want the design to withstand any kind of faulty user requests. My questions are how should I design ...
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0answers
93 views

Proper design of routes in Database MySQL

I'am trying to find out the best database design and try to stick with data integrity by using Foreign Keys. But I'm stuck right at the beginning because of limit relations between tables with FK to ...
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2answers
467 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 ...
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1answer
210 views

Foreign key double inheritance SQLITE

I'm designing a domotic system database and I'm trying to figure out how to represent two foreign keys. This is the cardinality I want. Consider 1...N Areas (rooms, halls, kitchens, etc.): Area 1 - ...
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1answer
90 views

Get data from Berkeley DB with Java [closed]

I have a basic Java program which can list data from Berkeley DB database. The question is how I can list the database scheme to see what object are available? Unfortunately I don't have information ...
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0answers
23 views

Modeling for inclusion of two different entities

What I Have I am currently hashing out the data model for an application that will utilize MongoDB. In my setup, users or members (as they are called in the schema) will be created and then assigned ...
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3answers
121 views

How to store list of unknown size in database

I have trouble with database design and don't know how to overcome this. The problem is with list of cities between two chosen city. User chooses start and finish city, and OPTIONALLY, user can write ...
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3k views

Need help to create chat application database schema?

I am developing a chat application in asp.net using SignalR. Client requirements are: Admin can create different chat rooms e.g. (News Room, Sports Room, Android Room etc) Registered users can ...
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2answers
70 views

Is this database design correct?

I'm trying to represent this: A message can be sent to one or more recipients. A user (recipient) can receive zero or more messages (but he/she could receive a message only once). Is my database ...
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1answer
171 views

Is this a step in the right direction for normalization? SQL 'inheritance' and Many-to-Many relationships

Context: So, this is kind of a compound question, but they go together, and definitely wouldn't make sense split up into separate questions. I've been working on a new database for what will end up ...
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2answers
432 views

When normalizing a relational database, should multiple “type” tables be combined into one?

Before making substantial changes to the content, functionality and design of my website (I'll be refactoring everything, almost a complete rewrite), I'm setting up a new PostgreSQL database to hold ...
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1answer
3k views

Storing multidimensional array in MongoDB

I am attempting to convert a large MySQL database of product information (dimensions, specifications, etc) to MongoDB for flexibility and to move away from the restriction of a column based table. I ...
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1answer
488 views

Optimum design / structure for product data database?

What would be the optimum design/structure for product data database, where each product have many variations and many attributes? Attribute sets vary between products, and some attributes have values ...
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2answers
527 views

Oracle 11.2 using too few memory

it is about one year that I have changed my server from Oracle 10g to 11.2g (and also changed the hardware and Windows from 2003R2 to 2012). The problem is that with more than doubled cpu power, ...
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1answer
83 views

Is array serialization always bad idea?

I'm making form-generating app in php. I have Widget table with type_id (html input) field, and I would like to add options field, like width/height, step, range, etc. Different widgets do have ...
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98 views

Is there better way to design SQL tables

I need to design a quick application for small warehouse. I just want to check if there is a better design approach. I am using polymorphic associations for comments tables. Business Rules If ...
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2answers
215 views

Keywords - column or separate table

I am building a website on MySQL with php, and I have 400+ products in a table. I have three columns with comma separated values, each has 1-3 values separated by commas in each row. I was wondering ...
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2answers
670 views

Storing a music playlist, best approach?

I am working on a web project that creates playlists online based on youtube links. My question is how do I store a playlist on MYSQL. What I was thinking about doing was having a table with ...
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1answer
104 views

Lookup tables and performance

I am using 6 lookup tables in my mysql database. There will be frequent insert,update and delete queries in the db. Will that badly affect the performance. Do I need to save the data as it is without ...
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1answer
295 views

Is this many to many relationship correct? [duplicate]

I'm reading this tutorial, and I have question about it. Look at this picture: 'Reading' the logical Relationship I read that a Project must have one or more Employee. But the physical ...
2
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1answer
127 views

Should I split these fields or leave as one?

I want to create a database listing characters in each book of the A Song of Ice and Fire series, listing the name of the character and the page in which they appear. I could just use three fields ...
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0answers
33 views

Preventing unique key constraint violation when pre-existing row has 'expired' [duplicate]

I have the following table schema; CREATE TABLE LOCKS ( lock_uid INTEGER NOT NULL, file_uid VARCHAR2(32 char) NOT NULL UNIQUE, owner VARCHAR2(255 char) NOT NULL, expires DATE NOT ...
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1answer
753 views

How to represent a many to many relationship with Crow Feet diagram

I'm designing a database and I want to represent the relationship between users and groups: A user can be on zero or more groups. A group can have one or more users. Using Microsoft Visio 2013 I've ...
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2answers
114 views

I don't know how to read many to many relationships

I'm reading this tutorial, and I have question about it. Look at this picture: Looking at Physical Many-to-Many Implementation I read the relationship this way: 'A user can be in zero or more ...
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1answer
183 views

Why do we not store names in a separate table?

Practically, I would never store names for customers in a separate table. But why not? It's a one to many relationship (a person can have one name but that name can be used by multiple people). ...
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1answer
139 views

Schema for dynamic number of attributes

I am implementing an application where users can save alerts for different services. Each service can have multiple types of alerts and each alert has X number of attributes to form a predicate. So ...
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1answer
509 views

HStore vs. multiple tables with inheritance - do I have a good use case for HStore?

My broader question here has to do with when it is appropriate to use HStore vs. multiple tables vs. one table for storing document-like objects. Now, for my localized example: I’m designing a ...
2
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1answer
69 views

Peer review database design for various reports

I'm currently trying to redesign a poorly thought out database for a peer review system that we use internally at my workplace. Employees can log on and submit a review about another employee who ...
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1answer
2k views

How do I connect my MS Access database to the LAN? [duplicate]

I wrote a database program in MS Access a couple of years ago, and it is used to keep track of some personal stuffs. I now want to expand this personal project and allow several computers to have ...
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1answer
456 views

desing the database for survey app with various types of answers

I have to create a survey app for which answers should be stored in the database. I created an html form containing some questions (about 30) with various types of answers (check boxes, radio buttons, ...
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1answer
61 views

Create menu from multiple meals relationship

I have the following relations: Meals(meal_id, name, cuisine, ingredient) Users(user_id, name, username, password, email) Chefs(chef_id, name, username, password, email) I want to create the ...
2
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1answer
166 views

Confusion normalizing data to 3NF and transitive dependencies

I am currently in a Database class and have some confusion with normalizing to 3NF. I have one specific issue that was not addressed in class but appears in the book problems. For example I have R ...
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1answer
539 views

Relational Model Design - Entity with one attribute

I am trying to design a database relational model for an assignment. First, I design the ER diagram, and then the relational model with tables (schemas). Here's my question: Is it possible for an ...
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1answer
1k views

Database design for mobile app

At first I would like to say hello to all of you, since it is my first post here on DB Administrators. I am writing an app which store drinks and their data. At the beginning it was storing all in ...
2
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1answer
203 views

How would I model the Twitter lists functionality?

I'm working on an application which would mimic the Twitter Lists functionality in which someone can follow someone else. Each user can also create objects which can be followed by users. The Twitter ...
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1answer
615 views

Multiple product attribute inventory database design

I have a database to build based on inventory for my shop. This is the current data that I have put into tables. This is the package: This is the product attribute: This is the table ...
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1answer
529 views

Airport Database Design guidance required

I am trying to make a generic database for airport management and DBMS would be oracle 11g xe. Since, i am amateur and still learning so i have tried to kept the problem statement simple with limited ...
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17 views

Database design and Technology [closed]

Can someone point me in the right direction for this scenario as I am designing a website: Its a portal where people can save customer details in the cloud. Now i want my main website to allow them ...
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0answers
26 views

loading k:v pairs from DB into JS Object

I'm creating a single player web RPG. I'm debating the following method of storing/retrieving quest items per player id: In userstats table, have a quest_items column of type mediumtext, where I ...
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1answer
154 views

Rules for Decomposition to 2 NF

I am struggling with the concept of 2NF form. Lets say I have a set of functional dependencies for R1(A,B,C,D,E,H,M,K) Where : B -> M,C AB -> D DH -> E H -> K A -> H Whenever I ...
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0answers
771 views

How to generate data for News Feed efficiently like facebook , googleplus , twitter e.t.c?

I have created table as post ( post_id int(15) auto_increment primary key , user_id int(11) , post_text varchar(2000) , post_type int(1), ...
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1answer
170 views

What is the advantages of using auto_increment in database as primary key over set of attributes?

I have table as CREATE TABLE circle ( circle_id int(11) auto_increment primary key not null, user_id int (11) not null, title varchar(255) collate utf8_general_ci not null ); CREATE ...
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1answer
138 views

What is the strategy of query evaluation in DBMS when Limit is used in query?

I have following tables in database post(post_id , user_id , post_text , parsed_text) ; Comment(comment_id , post_id , user_id , comment_text) ; friend(id , user_id , friend_id ) ; group (id , ...
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0answers
68 views

Relationship cardinality different in subclasses

I need to design a concert management database for as a class project. So far I defined an "Event" entity, subclassed in "Festival" and "Concert". Festival is intended to last one night or more and ...
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1answer
5k views

Airline reservation system [closed]

I'm making a simple airline reservation system. But I'm not sure about the design decisions I made. Concretely, I'm trying to implement following constraints: each Aircraft can have one or more ...