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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In regards to GS1 barcode - what size DB field are used?

In regards to GS1 barcode - what size DB field is used or is the entire GS1 typically not stored in database, but rather processed in the application layer and stored in the database as a collection ...
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1answer
110 views

Two types of data, so two type of databases?

For a social network site, I need to propose a DB. The application is written in Java & will be hosted on VPS(s) initially. Broadly classified there is two type of data to be stored at backend: ...
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26 views

Real time reporting on Mongo

I have my transactional data store as MongoDB cluster on which I need to setup real time reporting(may be a lag of 2 hours will suffice) Data size - 300GB with 20,000,000 rows and 40 columns and ...
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1answer
39 views

Having Non-Numeric values as measures in Fact table

According to my research regarding having non-numeric value as measures, I found that having non-numeric won't be an optimal one. So I planned to maintain numeric values. My scenario was "Employee's ...
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4answers
9k views

Is there a tool to check if my database is normalized to the third normal form?

I learned about normalization recently, and understand how important it is when implementing a new schema. How can I check if my database is 2NF or 3NF compliant ? Manual review is a sure option, ...
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17 views

Fan trap and redundant relationships issues

Here're a few domain rule resulting the current design of the relations. A project application form can have only one company responsible supervisor, and one company where the project is conducted. A ...
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1answer
45 views

Database templates [duplicate]

Are there any site with database templates for specific purposes? (i.e. a database schema for users and authentication in a webpage) for different databases like Oracle, MySQL... I have been looking ...
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14 views

Does an Object literal always mean the Predicate and Object form a key-value property on the Subject?

A triple is Subject-Predicate-Object, e.g. Post Office - Not Open - Sunday. Consider another example, Post Office - Size in Square Feet - "4000" For this example, I have two observations: the ...
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1answer
37 views

Computed Columns Or Views - Database Table Design

I want to store values in certain units along with their corresponding conversions. So for example, there would be following columns DateTime Millimetres Centimetres Metres For a ...
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0answers
30 views

Managing logs generated by user

I am developing a web app for my client and there is a section which displays the changes made in the application by any of the user. This section is known as log.It basically stores and displays the ...
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0answers
16 views

DBMS for working with sets [closed]

I want to simulate some stochastic system which deals a lot with small sets of integers, e.g. [0,1,5],[2,5,7,9,11]. The number of the sets is so large, and I need to look them up so often that it is ...
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1answer
29 views

How to Prevent a Many to Many When Number of Rows Shared Is Unknown

I have two tables that look like the following: Subjects id|subject_name|..some other columns 1 |maths | 2 |english | 3 |science | Users id|username|...some other columns 1 |Frank1 | ...
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2answers
77 views

Is this db/table structure sensible?

I'm not very experienced in database design so bear with me. I've taken over a ruby/rails app. with a connected MySQL/innodb database. As I'm updating the server to the latest ruby/rails version I ...
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1answer
119 views

Non-overlapping rectangles constrained to a boundary

I am trying to model placement of parts on a circuit board. Without any meaningful constraints, my basic schema looks like this: create table part ( part_id bigserial primary key, name text ...
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1answer
25 views

How to model state change timeline

I've got an app where users can place orders for recurring delivery of a particular service. The orders table has columns service_id and state, where service_id links to the service the user has ...
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3answers
72 views

Is it better to create another table to possible null values in relational databases?

I'm designing a relational database to use in MySQL. I have the next situation: In one table there are fields that in the most of situations are NULL. The fields would be like: Table name: tabla ...
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0answers
55 views

DB schema for an invoice system with tiered prices

I've been hired by a payment gateway company that handles payments for its customers. Every month, a script is run and will charge each merchant for the bulk number of payments completed. The unit ...
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1answer
76 views

How to structure this data? (Many columns currently.)

Working in MariaDB, we're trying to figure out how to store this data. All of our other tables have been normalized and are working nicely, but this has me stumped. We have a number of objects and ...
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3answers
166 views

What is the term for a “wide”, non-normalized view/query?

A well-designed relational DB schema tends to have a relatively large count of relatively small, normalized tables — a cluster of snowflakes, I think, describes the situation. In order to ...
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1answer
41 views

Duplicate records referenced across different databases

I have a table holding 'People' data (about 70K records) that coexists with an 'Address' table so there's one AddressID per every person in the 'People' table. The idea was to centralize the data in ...
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1answer
30 views

Entries with 2 variables. Do I need to make 2 more tables by entries?

In the case of shipment carriers, I have a table with products which price and delay will vary with 2 variables. PRODUCT | SHIPPING DATE | PRICE Carrier 1 | A | B Carrier 2 | ...
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2answers
101 views

Large database design

I am new to database design and despite my research I can really only find basic examples on design which does not help for my situation. Currently using MySQL The problem I have is as follows: I ...
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1answer
116 views

How to select only few columns from a table in database? [closed]

I have a table which consists of around 200 columns where name of each one is col_i (i=1 ,2,..200).Suppose I have to select only first 50 columns, how should I proceed? I found about concat() function ...
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1answer
28 views

Working on a blog creation website; should I be creating a new table for each blog, or keep everything on the same table?

So I'm working on this blog creation website as a side project. I don't actually expect it to become anything, but I want to make it as efficient as possible, even if just for practice. The idea is ...
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57 views

Referral table structure

I need to make a simple referral system and I have a database table set out as follows: mem_id | date | refer_email | accepted And the meaning of such columns is the following: mem_id: The ...
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1answer
45 views

Multi-tenant database constraints

I have a multi-tenant app in PostgreSQL that has a repeated tenant_id column in each table to help isolate the tenants from each other. My question is, is there any sort of way that I can use ...
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2answers
80 views

Best practice for entry position indicators

My problem is, that I have no idea how I could cleanly make an index (not a real Table index, just an indicator) for each table row representing the entries position while each position must be unique ...
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20 views

Null Dimensions in SSAS [closed]

Several years ago 2008, I create a data warehouse using Business Objects. Business Objects did not process Outer Joins well and used SQL for all of its queries. Therefore, for every dimension I ...
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1answer
53 views

String to timestamp in datastage 9.1.2

Apologies for asking a question that I suppose is very basic. I'm just starting out with Streams. I'm trying to read a sequential files containing a timestamp field and a value field, like this: ...
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1answer
74 views

How to store iterations of similar datasets

I have a dataset that is stored across 20 or so tables, most of which have a few million rows. This data will be generated fresh each month, and compared to past datasets. I'm pretty new to ...
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13 views

Determining the 3NF based on functional dependencies

Given a relation R = {E M L T} and functional dependancies LT -> E, ET -> L, TM -> E, and E -> M , I know that the superkeys of this relation is TL, TE, and TM. For 3NF, the left hand dependancies ...
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1answer
49 views

Creating many-to-many relation on demand?

Users can join projects. Projects can have many tasks. Each user completes the task at their own time, they can also have some other user specific settings on the task like the priority in their ...
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3answers
77 views

designing a database with type and sub type

I am trying to build a publications database, and i want to develop a genre relation that has various (maybe look up tables) sub-genres attached. as an example, in the genre relation there would be a ...
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1answer
35 views

Is this a good way to model course assignments?

I'm having trouble designing a data model that allows for the following: Courses can have many assignments. Assignments can be defined recursively. e.g. "There is reading homework every tuesday". ...
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2answers
79 views

Three questions about Database design

I'm new to mysql,and I'm designing a database for my social network app, I got some questions about it. user_table comment_table 1.Should I use unique key as much as I could in the database ...
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0answers
86 views

best way to log large amounts of data

I'm building a new logging system for our company. I'm wondering about the best way to store about 50-100GB data each year. I'm looking at both MySQL and MongoDB. I'm considering MongoDB because it ...
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1answer
51 views

Database design: handling time

I am developing a weekly timetable which ideally would allow teachers pick what subjects they teach. While most of this is fairly straightforward, from a conceptual point of view I am unsure how to ...
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18 views

What factors would cause me to favor inheritence over composition in a small database?

I have identified two choices for how to model addresses in my corporate entity database. Method 1: inheritance Table 1: Addresses [data table, primary key = (id)] id (integer) - primary key ...
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39 views

Loop through fields on a before-insert trigger?

Here's my table: CREATE TABLE foo ( i_am_pk CHARACTER VARYING(255) PRIMARY KEY NOT NULL, dont_touch_this CHARACTER VARYING(255) NOT NULL, name CHARACTER VARYING(255) NOT NULL, addr CHARACTER ...
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1answer
45 views

Creating a flexible table containing prices and periodes

I'm creating a system of availability for rooms and with a calendar according to the days, with every day have it's own price. Room Type | 01 | 02 | 03 | 04 | 05 | ... | 31 | ...
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1answer
47 views

Entity ID field that can refer to multiple tables?

In designing both audit tables and notification tables, I've run into an issue where I need a row to refer to an entity in another table, but which table that entity is isn't always the same. For ...
2
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2answers
146 views

Is it acceptable to have circular foreign key references\How to avoid them?

Is it acceptable to have a circular reference between two tables on the foreign key field? If not, how can these situations be avoided? If so, how can data be inserted? Below is an example of ...
6
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2answers
2k views

Unknown Db file format - best way to find out?

A client has given me the data he wants visualised in my project - but I don't know what DB format it's in. He's pretty unclear, also.. I have access to the table structures, but don't know how to ...
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2answers
176 views

No suitable driver found Orientdb jdbc driver

I have some problems with Orientdb driver for jdbc. i´m using Netbeans, i have include the library JDBC+OrientDB libraries (orientdb-jdbc-2.0.8-all.jar) in the directory and in netbeans, i have also ...
3
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1answer
46 views

Should I create a extra relation-table when I have two columns in one table referencing to one column in another table

My problem is best explained by example: Suppose I have a database about chess games and players. Which one of the following structures should I choose Option 1) player (player_id,name... etc) ...
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2answers
43 views

Should a table have a foreign key to another table if it already has a foreign key to another table that has that foreign key?

That was a hard title to digest even for me so I'll break it down. I'm very new to SQL, and I just designed my first database. I also am not very good at JOINS which might be the answer to my ...
3
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1answer
1k views

ERD via Chen's notation: How do I organize multiple 'last done' entries?

I'm having an issue creating a little practice ERD. I'm trying to do some more difficult stuff, and I'm not sure what the standard way to organize it is. Basically, I don't know which of these is ...
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36 views

DB Design for Mobile App Clients

Hello I am new to designing DB for Mobile App where speed is the Key. My Mobile App will request to WebAPI and WebAPI will get data from MySQL. I have designed my tables in MySQL as per relational ...
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1answer
59 views

How to store a version sequence per product

I need to create a table like the following one: +----+---------+---------+ | Id | Product | Version | +----+---------+---------+ | 1 | 1 | 1 | | 2 | 1 | 2 | | 3 | 2 ...
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5answers
48k views

Matching single column against multiple values without self-joining table in MySQL

We have a table that we use to store answers to questions. We need to be able to find users that have certain answers to particular questions. So, if our table consists of the following data: user_id ...