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

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2
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3answers
839 views

Physical Address Schema

I'm looking at adding addresses to an existing database, and am trying to work out the advantages and disadvantages of the following methods (and if there are any I've overlooked). Store the address ...
6
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2answers
482 views

Definition for “logical difference”?

I'm currently reading "SQL and Relational Theory" by C.J. Date. And although I'm quite far in the book, I've got a few basic questions. I want to know what the term "logical difference" means, The ...
1
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1answer
181 views

Foreign key to subtype or super types?

I'm using SQL Server and in this case i have the following tables: Restock: Foreign key to an R&D Staff member R&D_Staff: subtype from Staff Sales_Staff: subtype from Staff Shipping_Staff: ...
7
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2answers
2k views

Implementing a one to zero or one relationship in SQL

Let us say that I am designing a database for a scenario where there exists a one-to-zero-or-one (1-0..1) relationship. For example: There is a set of Users, and some Users may also be Customers. ...
2
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2answers
705 views

Generalisation in databases

I am working on a Hospital Management project in DB2. I have one table for staff with a primary key of staff_id. The hospital has to have different staff... e.g doctors,nurses,e.t.c. Is it better to ...
2
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3answers
4k views

Sorting by DATETIME slower than by TIMESTAMP?

I have the a DATETIME key on which I sort the results and the query is running quite slow. Will it run faster if I change it to TIMESTAMP ? Because I noticed that ordering by numbered keys is done ...
3
votes
1answer
745 views

Do I have duplicate key indexes?

CREATE TABLE relations ( object_id BIGINT(20) NOT NULL PRIMARY KEY, object_term BIGINT(20) NOT NULL, UNIQUE KEY link(object_id, object_term), CONSTRAINT fk_term FOREIGN KEY(object_term) ...
3
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2answers
3k views

6th normal form, Recomposition query, efficient implementation

I found this paper written by Hugh Darwen for avoiding nulls in my database: Link, It describes how to implement databases in the 6th normal form so you can avoid nulls. The logic is described in the ...
1
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2answers
216 views

Designing an Accumulating Snapshot with Repeated Groups, need advise

Situation I need to create a pie chart that has to be able to be represented at the following levels: District, Region, and School. At the student level it has to show the trend of the student over ...
2
votes
3answers
265 views

Should I create a separate database table for temporary users

I have a user table that controls access to a website. We currently have a few hundred users and this might eventually grow to a few 10,000s. We have a requirement to allow in "temporary" users. These ...
1
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1answer
2k views

User system database design

I'm designing a database for a new project and I'm looking for some feedback on the design before I start to implement/test. It basically consists of users, events, user profiles and a messaging ...
1
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3answers
6k views

how to Export a document contain tables name, columns names and column description from SQL Server 2008?

I created a db in sql server 2008 and I wrote for some columns description to describe them, What I want now is to find a way to export these tables design including the description for each column ...
1
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1answer
654 views

Stock management - needs suggestions

I need to create a database which will have below modules: Items [Food items, stationary] Items Stock Management [stock in out] Customers Items Sale Management Issue: The system will have ...
0
votes
1answer
120 views

database normalization and optimization for postOffice DB

I am designing a web application for a post office. Performance in database is critical for them. I have designed the below structure for the post database, is there any flaw in my db structure which ...
2
votes
2answers
997 views

Logical schema development and migration tool for different physical schema available including triggers and stored procedures?

We are planning to support for our application another rdbms (oracle). At the moment we are design our database schema with the MySQL-Workbench. For every new database version we have schema er-...
3
votes
3answers
745 views

Handling attributes that are time-variant in a Datamart

I have looked through the entire list of sites, and this is I think the best match. This is not really about database administration, more like database design. Please excuse me and point me to the ...
0
votes
1answer
97 views

What model design supports both data store backed and free form entries?

I have an application where users are tracking a workflow around producing a derivative work from an existing Book. The derivative work, we'll call "BookDerivative" must have a book that it relates to ...
0
votes
1answer
167 views

What are the first necessary actions needed to help secure a database's schema & data? [closed]

This smells like an open-ended, opinionated, wiki free-for-all, but I'm not trying to make this a battle of opinions. It seems like there should be a good checklist out there for all to agree on ...
5
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1answer
110 views

Possible pitfalls of condensing 2 SQL Server instances into 1

I currently have 2 SQL Server 2000 database instances (each running on a different physical server), each containing around 12 databases (not all are active). We are planning an upgrade to SQL Server ...
3
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1answer
1k views

Webapp & MySQL: Row Level Security

I am trying to emulate row level security on a webapp I am developing using MySQL. Using this method: Creating a database with the the required tables where the data pertaining to all the users will ...
4
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3answers
1k views

Single versus Multiple databases

I am working on a hospital management system using DB2 with pureXML. Is better to use a single database for all the data (patient, doctor details, appointments, history, medicines, etc) or to use ...
1
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2answers
1k views

serial field issue

Q: I use a serial as a datatype for my primary keys in my tables. I insert a lot of data then truncate these data one after one many times to test the data entry. My question is: Is there any ...
2
votes
1answer
444 views

In DB2, what are the alternative ways of evaluating an index's (or several indexes) benefit?

I'm trying to evaluate different approaches to analyzing the benefit of changing the set of indexes that are available. If I pick some representative queries from my workload, I can run EXPLAIN and ...
1
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1answer
132 views

Is maintaining a single database an issue when the underlying project becomes larger?

I have seen this related post but it was more focusing on the amount of consumers for the databases, which is not my only problem. I have a situation, where I am taking part of the design of a new ...
4
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2answers
1k views

Constraint many to many table between two child tables

New to this exchange site so I hope my question isn't inappropriate. Creating a somewhat normalized database I had one design problem I'm not sure how to handle efficiently. One table has a One-To-...
0
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3answers
970 views

How using many tables and JOINS affect performance vs. using limited number of tables and lesser JOINS?

I want to design a db schema concerning a schedule. I. I can use all fields in the same table, for example: id | shop_id | mo (varchar) | tu (varchar) | we | th | fr | sa | su 1 | 1 | 08:00-...
1
vote
2answers
1k views

Can we decompose a schema into BCNF when it is not even in 1NF

Given a schema r(A,B,C,D,E,F) and a set of functional dependencies A --> BCD BC --> DE B --> D D --> A As we can see the schema is not even in 1NF as can be read here, now the question is can we ...
1
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1answer
305 views

Design Tagging module in the database

I've a database system which we want to define tags for many tables into it. For example I've videos, photos, ... different entities that we wish to make them taggable. The tags could be anything. By ...
10
votes
3answers
11k views

One Big Database vs. Several Smaller Ones

We have a situation were we can (A) deploy instances of an applications in one MySQL database using table prefixing or (B) use different MySQL databases for each instance of the application, for e.g., ...
0
votes
1answer
609 views

Oracle: Extract Graphical Database Representation [duplicate]

Possible Duplicate: Oracle Creating ER Diagrams and Data Dictionaries How can I extract a graphical (schema) representation of an Oracle database (tables and their relationships; with colums ...
3
votes
5answers
841 views

Pros and cons of having one table per entity vs. having a shared table with an extra column indicating the entity type

I am working on a database design and am wondering about the pros and cons of two setups. I am going to collect data about two types of entities, lets say cars and boats. The structure of the data ...
12
votes
3answers
9k views

Best way to design tournament database

I'm creating a webpage for placing bets on all matches of the upcoming Euro 2012 football tournament. Need some help deciding what approach to take for the knockout phase. I have created a mockup ...
1
vote
2answers
355 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 ...
1
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2answers
768 views

Reporting Database Considerations

We have a very large database that we want to write almost real time. We want to take data and move it to another instance of the database on top of which will be a GUI and MI tool which will be able ...
1
vote
1answer
944 views

Does composite cluster index affect performance of seek/scan non-cluster index which is part of the composite?

I have bank transaction table with columns Division Brcode TrDate ProjectCode Accountnumber EffectiveDate DrCr Amount EndBalance In the other table the Brcode itself is unique and is assigned under ...
2
votes
1answer
553 views

Pros and Cons of having additional columns in join table of many to many relationship

I searched but did not find any discussions on this topic. Are there any pros and cons on creating many extra columns on joined table? Does it affect speed of data retrieval because we are joining 3 ...
6
votes
2answers
2k views

Recommended model for application level event logging

I am going to be storing application level events (user A added thing, user B updated that etc) for both public and private consumption. Below is an oversimplified model of the tables and their ...
5
votes
3answers
947 views

What are the pros and cons of using my customer codes as a primary key?

I am designing a database for one of my sales teams. Right now, the goal is to get a master list of customers and their mailing addresses, but the DB will eventually expand to track some other ...
6
votes
3answers
1k views

How to normalize Time Sheet data?

I am having a terrible time finding an appropriate way to store this data in a database. The current excel (simple) version looks something like this: http://i.stack.imgur.com/BEZOw.png Staff and ...
5
votes
4answers
4k views

Are there any free online collaboration database schema tools? [closed]

I am interested in a free and simple MySQL tool which can offer online collaboration functionality in creating database general schema. Do you know any?
11
votes
4answers
11k views

PostgreSQL designing tool [closed]

I am about to design a database which is going to run with PostgreSQL. I am used to the magnificent tool called MySQL Workbench for MySQL database. It is useful and it looks good which I kind of ...
13
votes
2answers
2k views

Why can't I use NEWSEQUENTIALID() as the default value for my column?

I'm trying to create a table in Management Studio and after reading about the new (from SQL 2005 on) NEWSEQUENTIALID() function, thought I'd give it a go. This is what I'm doing: But it's not ...
8
votes
1answer
778 views

Concept of Schema in PostgreSQL

I am not able to understand concept and usage of schema in PostgreSQL. I have no idea how it can affect my database design. Why should I use it? Can it affect me in future if I decide to not think ...
1
vote
1answer
83 views

Design for a Testing system

I want to redesign a part of my system. I got the following objects: Site: id Name Site Version: id idSite Name Task: id idSite Name Test: id idTask Name TestResult: idTest idSiteVersion ...
6
votes
2answers
2k views

Best way to handle dates prior to 1000 A.D. in MySQL?

I am creating a database for records that extend prior to 1000 AD, but MySQL Date and DateTime fields only support dates starting at 1000. Is there a way that would be more convenient than either ...
-1
votes
2answers
588 views

Diet and exercise schema

Pardon the brevity but: I am currently working on a project which requires users to create a 12 week diet/exercise regime. I basically need to store 3 meal options for each day which can be made up of ...
2
votes
2answers
783 views

Can a 2NF relation be M:M?

I have recently learned about 1NF, 2NF, and 3NF. I understand the definitions and the differences. I also had learned earlier about removing M:M relationships from a conceptual model by using ...
5
votes
3answers
2k views

Scalable table structure for periodically updated stats that get aggregated over time

I receive statistical data every 30 seconds that I want to store in my database so that I can analyze later. For example, every 30 seconds I could receive the number of oranges sold at a store in the ...
0
votes
1answer
506 views

How could I handle heavy load and consistency for product inventory in online retailers? [closed]

I have posted that question on Stackoverflow and they suggest me to repost my question here, as it would more likely to get help from a DB community (regarding this issue). Hope you guys don't mind. ...
4
votes
3answers
4k views

indexes, foreign keys and optimization

Not a DBA so pardon my ignorance... I have a table with 20 fields of which 8 are foreign keys. Mysql has by default added an index for each foreign key. Table has about 100k rows. When retrieving ...