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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How to store user's language knowledge (150+ languages) in mysql DB

Users in my website must be able to select languages they know (English, German, etc), so I have a table languages with 150 languages (id, name) and table users (id and a lot of other fields). ...
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2answers
124 views

Daily snapshot fact table

I have a list of products per costumer. Costumers can delete or add products to their list. I want to know in each day what is the list of products (and count) by costumer. My first approach is to ...
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1answer
68 views

Need Advice on Normalizing Database

I have a group of database tables that lack normalization. They all have a similar primary key called 'doc_index', which is either a PK by itself or part a composite PK. As you can see below, there ...
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1answer
22 views

How can I automatically add a foreign key to a table on select which is stored in an associated other?

I have a database with some tables among wich these 3 : organizations organization_id PK teams team_id PK team_organization_id FK users user_id PK teams_users tu_id PK ...
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0answers
29 views

Oracle 11 table design for better performance for reports?

We have a requirement to design a report page. A few factors we have are: number of fields in report is 70 computed fields is going to around 14*8 (based on toggles) a filter is going to have ...
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3answers
42 views

Removing chat history for a particular user from database

I'm currently developing a web chat application using SignleR and SQL server this is my database schema so far I've added an option where the user can Clear Chat history for a particular ...
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1answer
106 views

Database Design for NoSQL Fantasy Baseball League

I am trying to create a proper schema to place scraped data into, using a MongoDB database. Currently it looks like Team { id : id, name : String, teamLink : String, username : ...
2
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3answers
94 views

Tracking events in a task database

In designing a task database with the usual set of tables (Users, Tasks etc), I'm wondering if there is an accepted way to track changes to fields in the task table? I could just provide a text log ...
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0answers
14 views

Launching an RDS in a private subnet in VPC and access it from a web application [migrated]

I have setup a VPC which has two subnets. One is a public subnet (I have Internet Gateway attached to it) and the other one is a private subnet. My web application resides inside the public subnet and ...
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8answers
7k views

How do long columns impact performance and disk usage?

In our current project it just happens too often, that we need to extend columns by a couple of characters. From varchar(20) to varchar(30) and so on. In reality, how much does it really matter? How ...
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2answers
78 views

Database Design Help: MySql/PostgreSQL Single Database/Multiple Databases

We are planning to build a web based custom business analytics tool using PHP and MySQL/PostgreSQL. In our application, we are planning to upload customer’s data using a Excel sheet and these data ...
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25 views

Should I drop this column or is there a query that can achieve a results table without duplicate columns?

I use a column named active in several of my database tables to adjust whether a particular entry/row/user/etc should be included in future query result tables instead of deleting the information. ...
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1answer
19 views

Separation of users columns in another table

I've got a quite a lot of columns on the users table and I have been cleaning it up recently. Now since I'm searching over the users I figured it would improve performance if I separated verification ...
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0answers
43 views

Relational or non-relational database for a system to pass objects on?

hopefully this is the right place to ask this kind of question. I am working on a system that focuses on helping people give away things that they don't use anymore. So, an object typically has the ...
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1answer
28 views

Unique constraint to enforce max one null per item

I am using PostgreSQL 9.3. Suppose we are manufacturing some items of certain types, at any moment we are producing at most one item of a certain type. The following table captures our history of ...
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1answer
20 views

How to predict the growth of a PostgreSQL database

I'm looking for a way to predict growth of the database given its fields, indexes, constraints (as foreign key), number of lines, and so. I searched on Google, but I found only means to determine the ...
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0answers
28 views

Storing DB credentials in an application source code?

I am making an app which connects to a DB, and the app will have plenty different userslogins. Is it a good design choice to have a specific DB login/password for the application, using which the ...
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4answers
8k views

What is an audit table?

What is the function of audit tables? How are they useful? I came across them reading this article.
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1answer
65 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
11 views

How to model mappings at various levels

I'm trying to design the database model for my application and I'm finding it difficult to design the mappings for user access to various entities stored in the database. If access was only ...
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1answer
184 views

MySQL DB structure with Main category and several nested sub categories

I am looking to create a set of fields on my webpage identical to what eBay uses on their category selection page when you are selling something. For my purposes I am doing motorcycles, power sports, ...
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0answers
24 views

DB design, when to split out into schemas

I am building a storage solution to store important themes/concepts referenced in books. At a high level the system will contain one or more catalogs and each catalog will contain one or more books. ...
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2answers
34 views

How to enforce the structural constraints of rectangularly arrayed data?

(I'm particularly interested in answers that view the question below as a special case of the question: how should a RDBMS enforce structural constraints that are more specific than "one-to-many" and ...
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3answers
55 views

How to design database with january-december for every entry [on hold]

Need help for designing my database, I have a table named transaction with columns: tr_id, item, item_cost, item_quantity, total and my problem is: I need to divide the item_quantity from january to ...
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1answer
45 views

When to use hashtable over binary search tree vice verse for Database Index

Database Index can be constructed using binary search trees (BST) or HashTables , From my understanding so far , HashTables are superior to BST in terms of time taken for searching and insertions ...
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1answer
110 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 to produce ...
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0answers
13 views

How to test if a model is erroneous?

i am trying to realize why the following model is erroneous(or not). i am taking a database course and while i was studying I've found that model.
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2answers
45 views

What database should I use? [on hold]

I am writing a log analysis program in bash. As part of it, I am compiling a list of known errors, so that I can search and reference those errors as part of the known list. I originally was going to ...
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1answer
58 views

Create one-to-many to two fields in different table

I have a database where I am trying to figure out how to join a table that contains an object called ModelType. The calibration table contains two fields (EffModel and BkgModel) that are based on a ...
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0answers
27 views

SQL Server Database is corrupted - how to save it? [closed]

Respected Sir, unfortunately hard disk of my system is damaged, now I recovered my database. but it cannot be attached again to SQL Server 2005 Management Studio. The error is myfile.mdf is not ...
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2answers
28 views

Schema for storing historical data on shared identifiers

When user account is assigned an IP address, I create a table entry for the account/IP mapping. This data in the table is updated every 5 minutes. Right now I'm only keeping real-time data but I need ...
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1answer
47 views

Recipe Health risk Database ERD structure

I have these tables: First table(Recipe table), Recipe recipeid(PK,AI) recipename ingredients Second table(Ingredients table), Ingredients ingredientid(PK,AI) ...
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2answers
51 views

How to break table into two without losing performance?

According to http://stackoverflow.com/a/174047/14731, splitting away infrequently-needed columns frees up the cache allowing faster retrieval of the commonly-used columns. I've got a table whose ...
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2answers
29 views

Need Help maintaining multiple databases for a multi-tenant application?

i need some information about multiple databases for a multi-tenant application ? I am working on a project in which we are maintaining separate database for every company? The Companies Database ...
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0answers
42 views

How can I deal with a multi-record type field without breaking things futher? [closed]

If I remember anything about database design, I think this is a scenario where I'd use a combined key right? So I have. Note: Field1, Field2, Field 3, FieldX; Alert: FieldA, FieldB, FieldC; All of ...
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1answer
47 views

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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0answers
47 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 ...
3
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4answers
112 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
26 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 ...
2
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1answer
26 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
220 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
86 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, ...
0
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1answer
40 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 ...
0
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1answer
466 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 ...
0
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1answer
34 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
361 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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0answers
23 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. ...
0
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2answers
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 ...
0
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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, ...
4
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1answer
358 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 ...