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

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2
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1answer
858 views

counter table in mysql

i was going through the book: High performance MySql 2nd edition. In chapter 4 it says: An application that keeps counts in a table can run into concurrency problems when updating the counters. ...
2
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1answer
76 views

How to go about modeling the main object of relationship?

I'm using MySQL and MyISAM tables. I have a bunch of objects that I want to group together 1 object belongs to 1 and only 1 group 1 group can have many objects 1 group has 1 required main object ...
2
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0answers
232 views

Finding missing_index_details in MySQL

MS SQL Server apparently can tell you what indexes would be useful for your query. Is there anything similar in MySQL? This article (scroll to "Find missing indexes") says that in Microsoft SQL ...
2
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1answer
340 views

Bicycle Sharing Scheme - ER Diagram

Please compare the directions below to my ER Diagram and tell me if anything is wrong with my ER Diagram Please I think its accurate enough. Oxford City Council is preparing to launch an innovative ...
2
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2answers
256 views

Is unique index better than unique constraint when an index with an operator class is required

Postgres docs say: The use of indexes to enforce unique constraints could be considered an implementation detail that should not be accessed directly. One should, however, be aware that there's ...
2
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1answer
2k views

Foreign Keys with Composite Key

Imagine I have a table with the following dependency: (Name, BoughtFrom, TimeBought) --> Cost Where the three attributes in bold form a composite primary key for the table. Now then, I want to ...
2
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1answer
198 views

Is it ok to let users add new columns and tables to your database?

I'm basically making a database of databases. An administrative User can go in and hit "Create Database" (which is basically a table) and set up the column types and how many columns. Other users can ...
2
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3answers
835 views

File name as primary key?

I have a few tables I'm going to create for a website, Literature, video, and image. Is there a good reason why I shouldn't use the file name as a primary key. For instance... "someimage.png" as the ...
2
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1answer
923 views

Personal finance database design

I'm making a personal finance management application in PHP and MySQL, for learning myself some more PHP and MySQL. This system is currently using 4 tables: users, this table holds all the user ...
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3answers
238 views

Table naming and Database normalization

I'm creating a database of simulation results, and am trying to do so the right way. I've attempted to show relationships between data to make sure nothing redundant is thrown in. My current ...
2
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3answers
357 views

designing multiple tables while eliminating duplication?

As I'm working on an educational website, I'm facing a problem with my database design scheme - I can't find the correct design that eliminates duplication in the tables I'm creating. What I'm trying ...
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2answers
1k views

How do I properly design a many-to-many (charges/payments) accounting system?

This is just as much a db/programming question as an accounting/math question, so I'm actually posting to all relevant boards. I appreciate your patience in advance. Basically I'm having trouble ...
2
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1answer
106 views

Is it “OK” to have a table that only contain foreign keys?

In "OK", I mean "it doesn't have any bad impact with the overall database design". For example, will it cause insertion problems? or will it be a problem in the future when I add field in the ...
1
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1answer
202 views

Splitting a table based on business logic

This is mostly a design question and I'm looking for any feedback about the merits or flaws of this approach. Typically, I break database design into two categories, Business Logic and Recorded Data. ...
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2answers
356 views

Best type to use in a composite key when one of the values varies in type

I am building a data store for the content of multiple blog sites which have been scraped. Each of these sites is going to have an entry in a Blog table BlogId Url ...
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0answers
24 views

Database design - many-to-many relationship between three columns [duplicate]

I'm noob in database. So don't mind if its a silly question.This is used in my application and is the first one. I need a database design for it. value 4 is dependent on the other value 1,2&3. ...
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2answers
255 views

Relational Model vs. Database Products [closed]

The formal Relational Model (logical level) for databases is not exactly the same thing as you get with MySQL, Oracle or other major products / implementations of ‘relational’ database management ...
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2answers
1k 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 ...
1
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2answers
220 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). Isn'...
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2answers
683 views

Database model: doubly linked list

I am not sure if I get this right. I'm designing a database model for use in an application, and I'm stuck at a doubly linked list (model first; there is no code yet). There's an order. An order has ...
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3answers
294 views

One or several tables for attributes

I just spent some time discussing two alternative DB designs with a coworker and I'm not convinced. Neither of us is strictly DBA so we may be missing something. The overall goal is to create the ...
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1answer
120 views

Are there situations where queries are formed geometrically?

The topic came up in this other question. We were discussing sign value on a primary key having any significance. If there are good times to use geometry in building queries the sign value could be ...
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4answers
261 views

Better Indexing for MySQL?

Is it better to index each column individually with it's own key or to index multiple columns under the primary key? I've seen it done both ways in many different applications and I don't see a clear ...
1
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1answer
66 views

Apply Definition of MVD (multivalued dependency) to Example?

Supposedly this multivalued dependency (MVD) and this functional dependency (FD): {W} ↠ {N,D} and {W} → {N} hold in this table: V W N D ================= | v | w | n | 1 | -------------...
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1answer
59 views

Questions and answers database design for Core Data

I am designing database for a question and answer projects , and I am stuck. I do not know how to do it. Here is information: There will be many users There will be many questions Each question ...
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1answer
165 views

Database schema for entities with two possible owner/parent types?

I'm using PostgreSQL with Sequelize as my ORM. I have one type, User. The second type is Group, which can have any number of users associated with it through a GroupMemberships table. Users can also ...
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1answer
88 views

Load & traffic balance best practices

I am about to design an enterprise solution for a large scale application in which a windows service, MVC, and many other projects will use a database, so I am thinking about load balancing and best ...
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1answer
1k views

Multiple User Types - DB Design Advice

I'm developing a web application that will support user authentication with corresponding roles for each user. Also, my users can be of different types and have different fields associated with them. ...
1
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1answer
575 views

designing server side database to store user-specific data

I have a database with a number of quiz questions and answers. My basic design consists of these two tables questions (question_id, question_string); answers (answer_id, answer_string, ...
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1answer
89 views

Data structure design for supporting arbitrary number of columns in table or database [closed]

I am currently working on a sort-of a meta-modeler to build a free web service so that people can input data and run several models on that data. The task I am currently struggling is: user needs to ...
1
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1answer
805 views

Implementing Pub/Sub initiated from the database

I have a number of state-full Windows Services that currently poll the database looking for new or changed records in specific Tables and/or Views. For obvious reasons this limits scalability and is ...
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1answer
103 views

What to name a field that includes Store and Version ID

I am building a database that manages the definitions for a POS system (menu items, cashiers etc). It will include many stores and many versions. So, typical table will look like this (MenuItems ...
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2answers
140 views

Efficient workflow/queries to save unique information?

I am saving company information in a database. There is a single table with an auto-incrementing key that is unique to each company. There are separate tables for emails, websites, phone numbers, and ...
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2answers
101 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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3answers
123 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
121 views

Different kinds of pricing PostgreSQL

I would like to hear your opinion about handling different kinds of pricing. We have a product table which looks almost like this: +----+------+-----------+-----------+ | ID | Name | price_old | ...
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2answers
174 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 ...
1
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1answer
103 views

Low cardinality fields: integer or string

A Ticket has the statuses: new in_progress on_hold closed I could make ticket.status a string (on_hold) or an unique int(2). It is indexed. Int pros: smallest size in index Int con: low clarity ...
0
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1answer
2k views

What is the difference between int(8) and int(5) in mysql? [duplicate]

I found out, that if you have a field defined as INT(8) without ZEROFILL it will behave exactly as INT(5) in both cases the maximum value is −2,147,483,648 to 2,147,483,647, from −(2^31) to 2^31 − 1 ...
0
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1answer
71 views

What do you call numerical coding systems that are left-aligned?

I'm writing an importing mechanism for the NAICS database. I have a few questions about this code-format. I've seen it before and I like it the setup. I'm going to ask some other questions about best-...
0
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1answer
42 views

Database design help. many-to-many relationship

I have four columns. All columns are varchar fields. Three of them are independent and distinct fields having many to many relation between them and the fourth one is dependent on the combination of ...
0
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1answer
40 views

String templating technique

I am working on a fitness app that is going to deliver notifications to the user. I intend using MySQL events to populate the necessary tables, and then using an Ajax timer or Websockets or whatnot to ...
0
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1answer
1k views

Benefits of using Staging Database while designing Data Warehouse [closed]

I am in process of designing a Data Warehouse Architecture. While exploring various options to Extract data from Production and putting into Data Warehouse, I came across many articles which mainly ...
0
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4answers
124 views

SqlServer: can one table's PK be the FK of other two table's? [duplicate]

I have three tables project, users and proj_user. The PK of proj_user table is the FK of project and users table's pk e.g.(project_id,user_id) My question is, is it possible for the project_id and ...
0
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1answer
56 views

Split data across databases/machines

I have two questions about how to partition data across servers. Can I create and connect two or more databases, with the records correctly associated, using only a mapping table stored in a third (...
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0answers
24 views

Modeling question - Meta and instance

In a relational DB I'd like to model this: every customer_type has one module_set (1:1) a module_set has several modules (1:n) every module is different, and the user can activate them & reorder ...
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3answers
222 views

Design concerns for using 3x bit or one char(1) or one integer in table for holding status of item

I need to extend my existing table with status column. I am in doubt how to do that in most appropriate way regarding of future use of that status and performances of existing table. My table is ...
0
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2answers
152 views

To normalize or not

I'm scraping data from a website and they have pages for Users and Groups. The pages are pretty similar; id, name, description, created date, number of elements and custom background. They also have a ...
0
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2answers
440 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 ...
0
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2answers
980 views

SQL Server 2012. Update second table based on input from first table

I have two tables in two databases: Table01 in Database01 and Table02 in Database02. Both tables have a column called UserID. The UserID column is created when the user creates a new account on the ...