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

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Sum data from 3 tables(joining), but one of may no data then other tables data will show

I am making a stock group summary report for this I am making Sum data from 3 joining tables, but one of may no data then other tables data will show. I have 3 tables as: ac_stock_item, ...
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27 views

Is this solution correct?

We have the final relations of a database: Worker ( ID_W, Name_Lastname,Obligations, #ID_D) Department ( ID_D, Name_D) Vacation ( #ID_W, #BeginningDate ,Length_days) I have to draw the Conceptual ...
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34 views

Is double one to many a bad design? It looks duplicate when joining both one-to-many tables

Suppose I have user table, book table, DVD table. User can borrow n book, n DVD at the same time, a book or a DVD can be borrowed by a user. (I understand it is many-to-many situation in real life, ...
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34 views

Remove a parent entity in PowerDesigner

I have User table in a PowerDesigner logical model, which inherits from a base entity that has Id as int. I need to change this to string. I can't change the base entity's id type, as only one table ...
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13 views

Table mapping _ updating

I have three tables with inserted data so I want to update Value.Value with H.facility and H.Dep and H.CAT. Actually table V is the metadata of table H and table value has FK to V. I want to ...
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31 views

DB table structure for many-to-many relationship

I'm trying to develop a relational DB design which stores data related to aerial survey(s) conducted off of the coast. The DB stores the actual data collected, as well as design parameters. The ...
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1answer
54 views

sqlite database table with 1000's of columns

I am using sqlite3 in an application to conduct an alalysis of distances between sets of points. Distances between these points have been precomputed using dijkstra's algorithim and left me with a ...
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35 views

Relationship between favorite and contact in database

I am making an E-R diagram for my contact project that simply has contact and favorite as tables. Both of them has the same attributes(ex:id,name,number). What is the relationship between such ...
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45 views

Query other database's INFORMATION_SCHEMA tables

I have a shared database that stores procedures for all the other databases on the same server. This helps maintain one instance of a procedure rather than copying it across all databases. As long as ...
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37 views

Joining 4 tables of which one is unrelated

I have 4 tables as follows. I want to find a wholesum resultset, limited to 25 records, in the following way: Users from Table1 based on a condition And those Users should not be in Table2 [Non ...
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69 views

Updated Financial Database Design

I took the design that @Daniel Hutmacher suggested in question below: Financial database design I amended it as to what I need below: -- Companies CREATE TABLE companies_list ( [code] int NOT ...
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2answers
67 views

Document Store & Relational DB Hybrid. Exists? Possible?

Does anyone know of any product or open source project that attempts to strap together Mongo DB and MySQL for instance? I hear a lot about how relational DBs being ACID compliant makes it nearly ...
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41 views

Best to isolate the database in multiple instances?

I read on a forum about the use of database isolated environments are neccessary for any large project that handles "big" data. For instance I will be using the following table for ALL blogs: ...
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54 views

DB table design for attributes with multiple entries (eg: Person -> Social Media)

I am trying to decide the structure of a DB table to store Employee data. I am bit confused on how to design attributes such as Address, Social Media etc. There should be provision for multiple Social ...
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29 views

What is the db-structure behind sites with multiple similar subdomains, like Stack exchange?

own db for every subdomain 1 big db used by all of the subs own and shared db-s used by the subs When to use the 1st/2nd/3rd approach? Thank You!
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181 views

Database Design for group chat

I am creating a chat system as a RESTful API. This is what my design looks so far A request can be made to fetch the newest 50 messages that are part of a group id. Even if I do get a list of ...
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38 views

Database calculations question

I am creating a MySQL database that is going to be used to store a lot of timestamps. There are currently 6 timestamp fields that data can be entered for one row. I am utilizing timestampdiff to ...
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1answer
37 views

Google datastore modeling help

I have a very simple requirement. I have an application where users log in, add/remove/view friends, and can send/receive (also view the message you sent and received) a message (message is more like ...
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23 views

Handling Login of SAAS application end users

I am designing a SAAS application with multi-tenant database per-user-per-database with unique sub-domain of subscribed users. The question arises when subscribed user of saas application add more ...
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33 views

Dealing with multiple user types, modules and requirements

I have the following database schema. Basically, it all comes down to this: - users can have multiple user types - some user types come with specific requirements for a complete profile - there are ...
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1answer
36 views

Database Design - I have a question regarding joining tables

Forgive me for my dumb question but I am new to Ruby on Rails and data design. We all have to start somewhere right? Well my question is that I want to build a database for a Truck driving company. It ...
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37 views

Is this pattern named and how to normalize it?

I am given a data table : State ( StateId, StateNme, StateCounty1, Statecounty1Seat, StateCounty1Rep, StateCounty2, StateCounty2Seat, StateCounty2Rep, StateCounty3,...... ) ...
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43 views

database design for a filing system in educational website

i'm designing a database for a filing system in educational website. user can upload files ( files_table) user has a library (library_table) user can add a file to his/her library each library ...
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27 views

Help creating database schema to build database off

not sure if this is the right area for a question such as this but I am looking to create a database for an IS warehouse who deliver laptops, desktops, monitors and other peripherals to different ...
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23 views

When is it suitable to turn a table around [duplicate]

When I create tables to store data in, I have columns for each property of the model to store. IMHO this type of table design is easy to read and logical. Example below: uid | firstname | lastname | ...
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39 views

Generate incrementing IDs without sequences

Suppose there's a multi-tenant application where users can create some kind of documents with basic structure like CREATE TABLE users (id SERIAL PRIMARY KEY, email TEXT); CREATE TABLE documents ( ...
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54 views

Database schema for storing edits in the content [duplicate]

I want to store all the edits of a specific table. Multiple fields can be modified and for different users. I want to store all changes, taking in count that the number of fields that can be edited ...
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2answers
60 views

Optimal database structure for fast inserts

I am using MySQL Percona server. This table needs to do fast bulk inserts using 'INSERT INTO ... VALUES' for smaller requests (about 100k records) and using 'LOAD DATA INFILE' for larger (up to 10kk ...
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26 views

ER and Precedence Diagrams

I've been having some difficulties creating a "Cruise Ship" database. Basically, what is known to me: Office has information about: Route (final destination/target) Ships Room Room's class (rank) ...
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30 views

Data Model for a popular/basic type of social app

I am trying to learn about Google Datastore and creating a basic application to have some practical experience with it opposed to just reading the docs. I would like to create a basic social ...
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118 views

“mysqld got signal 11” error

I have a MySQL 5.6.22 InnoDB database and just now, suddenly out of nowhere, when I try to start it up using /etc/init.d/mysqld start, I see this error in the error log and the server won't start up : ...
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20 views

Do I need to create models if im not going todo anything with that data

I am building a online golf team entry form. I am getting confused as to what models I really need. Basically there is a few leagues and zones(divisions) and in each zone there are 8 fixtures and at ...
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52 views

How do I design a database for a registration system?

The concept is something like this: Organiser creates event. User registers for events. Events can be for multiple days. One event can have different competitions. User can enter into any ...
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1answer
50 views

Table design for a dictionary that can have words with many different spellings

I'm working on a small, personal dictionary database in Microsoft Access (the 2013 version). There are a lot of words in English that have two or even more spellings. Realistically speaking though, ...
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2answers
69 views

Database design for millions of posts

I have this issue. I have three types of posts a user can generate (some users can generate all some can only generate one type). I have the following types: main, employee and admin posts. I ...
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1answer
125 views

Database design for products with multiple units

I am designing a database for retail business. There are some products that can be sold in multiple units, for example, pencils can be sold in ea and dozen, paper can be sold in sheet, ream, and ...
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1answer
40 views

Designing a database where records can reference different foreign keys

I can use PostgreSQL or Microsoft SQL, whichever provides the needed capabilities. I need help designing a database that has records that can reference FKs in different tables. Given the following ...
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1answer
28 views

Table design: paired values of genetic data

I'm trying to decide the appropriate way to design my tables to store my genetic data. Basically, I have samples, and each sample has multiple loci (a locus is basically a point on the genome), and ...
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356 views

Table design for a simple messaging system (ala Facebook or whatsapp)

I'm trying to build a very simple messaging system: a list of conversation with shows the profile pic of my contac, the last message of that conversation and conversation not read will be ...
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32 views

What is database storage structure?

I'm curious that there is a term "storage structure" in the context of databases, but there is no clear definition to be found in the textbooks. Wikipedia ...
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42 views

How to map this ER model to actual tables?

Suppose we have an ER-design problem like this: A pharmaceutical company sells its products throughout a country. For the ease of sales, the entire country is divided into some Areas. Areas have ...
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17 views

Please help modeling this basic scenario

I've already asked in stackoverflow but I think I was not clear enough and I couldn't get the answer I was looking for I'm trying to modelate a situation and I have a lot of doubts about wheter the ...
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101 views

Database design for storing historical stock exchange Level2 (depth) data

I am developing C# software using embbeded SQLite Database which shows historical level2 (market depth - asks/bids) stock exchange data graph. Example Simply speaking, there are 25 asks (price, ...
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1answer
46 views

Need help on database design

I have a huge database of library system but I have a problem on how to design tables on this database. This is because I have under one entity (for example AUTHOR) a lot of repeatable fields. So I ...
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16 views

build users availability report/Table (using sql)

I got a question from our product team to build a "Table availability of customer service representatives (user)". f For example : user_A was available to accept a call from 12:00 to 12:03, so I have ...
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24 views

Structure of an SQLite database for storing analytics with counters and hits

Before making this post, I referred to this and this which contain extremely complex solutions and hence, this question: I am building a spam filtering app that takes posts from a feed and deletes ...
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1answer
19 views

How can I differentiate between a Multivalued Attribute and an Entity?

While designing ER Diagrams, how can we differentiate between a Multivalued Attribute and an Entity? How can we know that, what we are considering as an 'Entity', isn't actually an entity but a ...
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17 views

ER diagram when having a condition

Can someone explain to me or point me to to the link on how to draw diagrams that have conditions. Example : you got a booking website that allows regular people to book or rent a room at some hotel ...
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2answers
41 views

Define a db before coding

I'm starting to code time tracking application to replace the monthly excel sheets my company is requiring. Its purpose is standard : to centralize all data about the time spent by different(or same) ...
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1answer
295 views

How does Snapchat store its data?

I am a highschool student who is interested in developing apps and learning more about databases and servers, so please bear with me if this is the wrong place to ask or if it's a obvious answer. I ...