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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Does a Key-Value type table still needs a auto increment key?

Suppose that I have a very simple table to store variable-like data, like this: +-----------+-----------------+ | key | value | +-----------+-----------------+ | site_url | ...
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21 views

How to handle many columns / variable schema?

I apologize in advance in case this question has been asked already. I'm working on revamping a reporting application used within my company. The requirements are: Support addition of new fields ...
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SQL Database is corrupted [on hold]

Respected Sir, unfortunately hard disk of my system is damaged, now i recovered my database. but it cannot be attached again to SQL management studio 2005. the error is myfile.mdf is not a primary ...
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4answers
94 views

How do I prove that the act of removing foreign keys doesn't corrupt existing data?

TL;DR: Prove that in practice, the execution of the alter table table_name drop foreign key constraint_name statement does not corrupt existing data. The important consideration is the execution of ...
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1answer
21 views

Max from 2 columns with priority date col then the seq col Oracle

I have a column xdate, column seqnumber, personID I want 1 record per personID, where it is the most recent xdate max(xdate) if there is multiple same max xdates i want it to look then for the max ...
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1answer
17 views

Hierarchy for dimensional model

I am trying to model a DW where I have many levels of geography (Neighborhood, District, City, State). I have several demographic data that should be included in the model. These data include count ...
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4answers
217 views

Arbitrarily ordering records in a table

A common need when using a database is to access records in order. For example, if I have a blog, I want to be able to reorder my blog posts in arbitrary order. These entries often have lots of ...
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2answers
84 views

Table design for multi-type data

The information model I am modelling from includes an "any type". For example a customer can have zero or more 'entries' each of which can have a number of values. Each value could be a either date, ...
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1answer
36 views

Building a branched versioning model for relational databases

I am database designer and at my current project I'm implementing versioning capabilities required to concurrently edit rows of data in RDBMS. The project requirements says, that data editing sessions ...
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1answer
453 views

Efficient way to move rows across the tables?

This is somewhat long question as I would like to explain all details of the problem. System Description We have a queue of incoming messages from external system(s). Messages are immediately stored ...
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1answer
27 views

Schema for multi-account database

I'm building an app which will have accounts for organisations leading to organisation.myapp.com subdomains for their account access. I'm putting together the schema for it and I have a few ...
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1answer
333 views

tables for different sources of payments

Selling software products. I have a table "licences". Each software licences is created due to a payment. I am creating tables to accept payments from different sources (e.g. manual or PayPal.) I'm ...
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22 views

Minimize table joins in design

Probably didn't come up with the best title, but I'll explain what I'm trying to do. I need to be able to track gym members, trainers, workouts, and gym locations. I've created a simple example below. ...
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17 views

Null column for username and password when using Login with *social network*

I want to know what are the conventions for columns like username and password when your application supports login with a third party, like login with facebook for instance. Given the fact that when ...
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1answer
101 views

Relation between multiple hierarchical taxonomies linked to a single entity

I am working on an online test application which supports multiple choice questions. I have created schema for taxonomy (classification) system to be used with questions. taxonomy(id, name, slug, ...
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1answer
309 views

Bad Design or Complicated Query?

Problem: For fun I am building a Database for lottery results to get some statistics off of. As of now I am only interested in a Pick 3 style lotto and might introduce more later. How would you ...
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1answer
21 views

How do I choose primary keys for star schema BI data warehouse?

I am extracting sales turnover data from a Microsoft Dynamics Database into another SQL database that will be used by the BI tool of choice. This data is coming from G/L (general ledger) entry items. ...
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3answers
803 views

Are there any tools to go from ERD to DB design and vice versa?

I'm learning DB design and looking for some tools, preferably open source software, that could help go from an ERD to a DATABASE and vice versa. For the record, the database i'm using is MySQL.
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62 views

Converted ERD into Dependency Diagram 1NF, 3NF

Thats the ERD. I'm studying for an upcoming test and having trouble getting my head around converting thes ERDs into dependency diagrams. This is from a previous exam that the Lecturer told us to ...
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13 views

Optimal layout strategies for Time-Series using Columnar storage

In the context of time-series and specifically columnar storage systems. Question: What are the processes or heuristics that are used to determine how best the columns of contiguous values be grouped ...
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39 views

MYSQL Indexes when looking up on alternating sets of columns

I have a table that looks like: CREATE TABLE `connections` ( `connection_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, `service_id` smallint(5) unsigned DEFAULT NULL, `parent_id` bigint(20) ...
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4answers
119 views

Mass data upload from Excel - technology

I am a Developer seeking help in terms of DB technology for a specific requirement. I have done some research but can not conclude with list. Requirement: There will be a web application which will ...
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2answers
162 views

Usage of foreign key when the referenced table data will not change

I have to design a table where user has 10 fields and 6 are dropdown. Some are single selections and some multiple. Dropdown data is supposed to change very rarely. For e.g., the user is presented ...
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79 views

Enforce referential integrity between two groups of data

I have two sets of records: A collection of rules. A collection of actions to perform based on those rules. What I'm trying to model is something like this: Multiple rules can be grouped ...
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3answers
104 views

Postgresql: datatype for email address

What would be the right datatype to store email addresses in PostgreSQL? I can use varchar (or even text), but I wonder if there is a more specific data type for emails.
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19 views

Correct Schema Design for form builder?

I'm attempting to build a form builder app that allows users to: signup build a form store the data from that form into this db. I have designed the following schema: ...
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1answer
58 views

Database design Problem for the web-app

Hello I am in a problem of designing a web-app database schema. Suppose I have 10 shops and every shop gives deals on every different day Sunday, Monday and so on and for limited time period like ...
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68 views

Should I use SQL Azure to store product descriptions and links to images in Azure Blob

For an html/Css/JQuery public Azure website to be coded using Zurb Foundation html5 responsive framework, I'd like to use SQL Azure (web edition) to store product descriptions and links to images that ...
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193 views

Best practice for a Table with private columns

I have a table with user data, where most of the columns can be public or private (so it will be shown or not on the app) and every user can decide which fields to hide. So far I had a couple of ...
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1answer
51 views

Train Fare Database Normalisation

I have a database to normalize. The database has details of train ticket fares. The trains have different fares depending on the distance and I have to store these fares in the database It is not an ...
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1answer
67 views

How do I add versioning to this CMS I'm designing?

As you can see, my CMS consists of several widgets (for example an Articles widget), of which you can create several instances, which I call blocks, and those blocks are linked to pages and the ...
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2answers
124 views

Optimizing large MySQL SELECT WHERE IN clauses

How can the following SELECT WHERE IN case be optimized? I have a table with over 100 million rows with only 3 columns. The primary key (col1) is a 127 varchar. I am performing a SELECT col1 WHERE ...
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2answers
55 views

Should a ledger DB store a separate line for each side of a transaction?

I'm working on a database that needs to do manage transfers between several accounts. We are considering using a simple ledger system for this (like what you find in Quicken). I have two concerns ...
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1answer
44 views

CRM Address table and it relation

Hi I want to ask about I have this DBD for my CRM I am trying to have the addresss in one table(customer and Employee Address) and both customerID and Employee ID are guid I have in address table FK ...
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3answers
2k views

How costly is opening and closing of a DB connection?

How CPU intensive is opening and closing of a DB connection (for a web app) in MySQL ... when the DB software is on localhost? ... when the DB software is on another machine?
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73 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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108 views

Should I add transitive foreign keys?

Simple example: there is a table of customers. create table Customers ( id integer, constraint CustomersPK primary key (id) ) All the other data in the database should link to a Customer, so ...
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3answers
892 views

Foreign keys - link using surrogate or natural key?

Is there a best practice for whether a foreign key between tables should link to a natural key or a surrogate key? The only discussion I've really found (unless my google-fu is lacking) is Jack ...
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1answer
33 views

modelling warehouse picking

What's the best way to approach modelling a warehouse picking system? To be precise, customers place orders which are processed by warehouse staff. A simple products and orders database isn't an ...
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1answer
22 views

Establishing referential integrity in a generic table?

Current Schema: - DropDown: DropDownID PK, Name nvarchar(25) - DropDownOption: DropDownOptionID PK, DropDownID FK, Name nvarchar(25), Description nvarchar(155) ...
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1answer
277 views

Designing Simple Schema for Disaggregation of Demand Forecast

I am doing a simple database design task as a training exercise where I have to come up with a basic schema design for the following case: I have a parent-child hierarchy of products (example, Raw ...
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37 views

Which is the better schema design for a voting system?

Imagine a q/a site or forum similar to stackoverflow. I'm trying to determine which of these two methods would be the better design for a voting system: (note: I would also like to keep record of all ...
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30 views

Tinder database structure? [on hold]

For those of you familiar with the way Tinder works, do you happen to also know the underlying database structure behind it? How it manages to store all the information, the memory efficiency, etc. ...
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2answers
38 views

how to design a database's table to store mysql spatial data in a parent child relation?

I want to store locations and polygon data in a parent-child relationship. I am using spatial data in MySQL and Google maps for polygon. Examples: 1. World 1.1 US 1.2 China 1.3 Japan 1.4 South ...
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17 views

Conditional value lists in MySQL

apologies in advance if the language I use here is insufficiently specific. Please let me know if there's anything that I can clarify. Does MySQL provide a means of creating conditional value lists a ...
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1answer
170 views

Should I save “document ID” as a String or Number in MongoDB

So I'm importing about a 100,000 documents into mondoDB. MongoDB already generates an Object hash but the data has a documentID that was used to identify records in the previous database. The IDs ...
2
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1answer
164 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 ...
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1answer
41 views

How to model when you could have many (thousands of) attributes to a table (product)?

We have a main table, let's say, Product. It has several general attributes like 'Product Name', Manufacturer ID, etc. As of now, all these attributes are implemented in the data model as columns to ...
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1answer
188 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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Identifying functional dependencies

I'm having trouble understanding the logic in use for identifying functional dependancies. Looking at the sample relation below, I understand fd1 - fd3. But when I look at fd4 and fd5, its logic ...