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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Geographic Synonyms

Let's say I have a table representing principal country divisions (ex States): create table principal_country_divisions ( id int primary key, name text not null, country_code char(2) ); insert ...
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Proper implementation of child (derived) table PK/FK during single and multiple inheritance hard coded generalization physical data model

Below is an image of hard coded generalization UML logical model of entities. I'd like to implement these classes as tables in a physical data model. Two derived classes/entities (Class2 and ...
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Tracking changes on a table

I have a users table. I want to keep track of all the changes I have done,name,phone etc. I've thought to create an extra table changes that will store the id of the previous and the next version of ...
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341 views

Temporal Validity and Primary/Foreign Key Relationships

I've read through several of the oracle tutorials that show temporal validity and time features. However, in the examples I'v read, there is no primary key used in the demo tables. ...
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3answers
184 views

Database design for excel-like data

The task I need to store the some values in sequence in the database. The data looks just like a sequence of numbers. Here is an example of the data: Val_1 Val_2 Val_3 ... ...
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112 views

Relation between lossy decomposition and Natural join?

I am confused with the lossy decomposition and natural join. Natural join(with common attribute): only respective common attribute for the resultant table is formed. Lossy: Natural join on tables ...
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95 views

Normalise an expenditure table in a budget database [closed]

We have a budget database that stores expenditure items per budget. There are over 100 expenditure items each having common attributes: Amount, Frequency, Comment. The table will have over 300 ...
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1answer
44 views

DB2 MQT not rewriting role playing columns

If in a MQT, if I have 2 referential constraints to the same table (role playing) , usage of one of the constraints doesnt allow the query to be optimized Example FACT_SALES DIM_BILL_TO_ID --> ...
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Schema for yearly data models

I am developing a school management system. Most data will not be reused after the end of the school year. I am contemplating using schemas to separate data in various school years, however I am ...
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3answers
410 views

Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...
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75 views

Inserting and updating on same table

I am currently working on a database that aims to provide information regarding the amount of time people stay in a company's car-park premises. This is done using a table called "tbl_stay" which has ...
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1answer
53 views

Is it more efficient to store 0 and 1 for a binary value or just empty and 1 in MySQL

Is it more efficient to store 0 and 1 for a binary value indicating whether a flag is up or down or just empty and then set 1 for rows where the flag is up. Using MySQL. E.g. Flag 0 1 1 0 0 Or ...
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Is it bad idea to create foreign keys on the tables in a different schemas in the same database for big applications?

I am working on the transfer a big pl/sql web-based application to the dedicated server. This application is located in one schema with 70 packages of programm code. This application was made ...
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3answers
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Uniqueidentifier vs. IDENTITY vs. Material Code --which is the best choice for primary key? [closed]

Which one is the best choice for primary key in SQL Server?There are some example code: Uniqueidentifiers e.g. CREATE TABLE new_employees (employeeId UNIQUEIDENTIFIER DEFAULT NEWID(), ...
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2answers
74 views

Store extra, optional information about any entity [closed]

I've done a bit of reading but haven't found anything related. This must be widely discussed, so it's most likely my fault. I've got a relational database with a number of different tables, each ...
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1answer
350 views

Polymorphic Association - is it bad? [duplicate]

In the following schema: Collections Upvotes Reports Upvotes Reviews Upvotes I'm tempted to have a single Upvotes table with a single "entityId" column that stores either the ...
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1answer
50 views

Database design implementing support for different languages [closed]

Today I was practicing database design, for example I was trying to build a database design where I would like to store my favorite shows. I have normlaised this database to the third form (at least I ...
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2answers
2k views

What is the best way to model an invoicing system with different forms of invoice items? [closed]

I am doing some preliminary database modelling for a Line-Of-Business application that I am creating. The application will be a Practice Management System for a medical practice/clinic. I am looking ...
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1answer
2k views

Database partitioning - Horizontal and Vertical sharding - Difference between Normalization and Row Splitting?

I am trying to grasp the different concepts of Database Partitioning and this is what I understood of it: Horizontal Partitioning/Sharding: Splitting a table into different tables that will contain a ...
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1answer
196 views

facebook group alike database scheme

Here are my requirements: one user can have many tasks one group can have many task one group can have many users only invited user by a user can be added into a group Does this db design appear ...
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1answer
839 views

Two-column foreign key constraint only when third column is NOT NULL

Given the following tables: CREATE TABLE verified_name ( id SERIAL PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL, UNIQUE (name, email) ); CREATE ...
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1answer
63 views

Is deriving a value using multiple joins a good idea? [closed]

I am working on a university project. I need to create a database from conceptual to implementation. That allows customers to create an order with multiple products the specification says that we ...
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1answer
523 views

Relationships between subtypes of an entity

I have a very big (hundred of milions rows) table which represent an entity (event) having many subtypes (different kind of recorded events). Each row is identified by an id (obj_id) and has an ...
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1answer
448 views

Database design for threading messages

I am not sure whether this question is suitable for this forum, but since it says Database Administrator I hope I am right. So my question is, whats the database design or business logic for creating ...
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1answer
635 views

Date of birth saving to MYSQL DB with timestamp or date column type [closed]

i am using MYSQL database and would like to know which of this is a good practice. way 1 - use column type in DB as timestamp. i.e will contain values like 2012-11-13 00:00:00 way 2 - use column as ...
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1answer
116 views

To normalize or not to normalizde? (10 fields)

I'm helping someone to design a database and for a specific case I'm not sure. I have 10 fields - this will never change - that will always be filled and used in every query that could be coming up. ...
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296 views

On which filegroup will constraints be created by default when adding them to a table on a filegroup and how should they be separeated?

We have multiple filegroups, that look something like this: PRIMARY (default) app_data app_index When I create a table on filegroup app_data CREATE TABLE Person ( [PersonID] INT NOT NULL ...
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2k views

Unable to access sql database with login and password [closed]

I'm writing Windows Service in C# and inside of it I'm unable to connect to the database. This is the question I've asked recently: SqlException: Cannot open database "path\db.mdf" requested by the ...
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36 views

Have a lot of customers -> which design in SQL Server 2008R2 should be chosen [closed]

I have a task and I don't know how solve it :) So, we have a lot of customers who should use SQL Server for their applications. Design is standard and simply: Customer -> Remote Desktop -> ...
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1answer
735 views

SQL Server performance for tables having large number of columns [closed]

I have a requirement where I need to create a table with about 600 columns. Out of 600 columns about 200 columns will be XML columns. Other column will be of other datatypes such as int, varchar, ...
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1answer
190 views

Precautions when designing database schema if tables are going to have billons of rows

I am about to start work on telephone dictionary kind of project. Its confirm that there are going to be billions of records in dictionary table, and each entry from this dictionary table may have ...
2
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1answer
2k views

Need for indexes on foreign keys

I'm struggling with indexes, primary keys and foreign keys... And the need of having them all. If I have two tables, both of them have an integer as a primary key. The first table references ...
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96 views

Datamodel design for multiple roles, country access

I am in the process of creating a data model for the below scenario there will be two hierarchies a) dept hierarchy (emp -> team -> dept -> branch) b) sales hierarchy (emp -> marketing manager -> ...
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153 views

Implementing foreign keys on generalized data model

Suppose the ASCII tree below is a UML generalized concept model. To represent these entities/classes in UML, lets assume [mammal] a super class, and the level 1 classes, [wild] and [domestic] are sub ...
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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 ...
0
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2answers
399 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 ...
0
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1answer
64 views

What is the “proper” way to design a database architecture when entry counts belogning to different users may vary wildly?

To give a context; we are going rewrite our application in Django framework. The database that is being used by the old system at the moment designed very poorly, without any respect to methodology of ...
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Database design to track inventory?

Would this be a good starting point for tracking inventory with several warehouses? If yes what is the best approach to sum quantity when displaying stock by warehouse/type/general? mysql structure ...
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235 views

avoiding unique key collisions across tables

This might be related to the idea of data warehousing, but i'm not sure, though it is extreme theory. We have a table where records get written to first, let's call it tbl_recording which looks like: ...
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1answer
61 views

is-a relation(ERM) to tables

i try to design a database with an is-a relation: Vehicles have some general attributes and the SubVehiclesX have some specialized Attributes. SubvehicleX is a Vehicle And a Person has a Vehicle ...
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81 views

How to check how the table structure effects the performance of my query

I want to check how the table structure of a certain table effects the performance of a delete query. This is not a generalised question, I have a table, with currently 2.2 million records ...
2
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2answers
216 views

How to establish a Two-to-One table relationship (PK-FK-CK)?

My question is about DB design and its principles. I am working on a Python application where objects are mapped to database tables. I have Projects and People objects, mapped to their respective ...
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1answer
218 views

Does my ERD account for my business logic

As part of my new and upcoming project, part of the business logic involves sending each and every one of my customers (assume they number in their 1000s) multiple (possibly customized) emails. Each ...
0
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1answer
112 views

Database design [closed]

I have tables college and department. In college, I have serial-number and college-names, In department, i have nos, college-names and department-name. My challenge is that having a repeated ...
2
votes
1answer
103 views

Method to keep track of large number of sets with high cardinality

We're building an analytics service. One of our needs is to maintain ~100MM sets each with anywhere between one member to 1MM members, with each member represented as a long. We need to be able to ...
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1answer
62 views

Accessing MySQL Database

I am designing a database for an application, which will be accessed by different front end programming languages, such as php, asp.net, android applications and iphone applications. I am confused, ...
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884 views

GUID stored in a varchar field

I have inherited several databases that use GUIDs as PKs. Instead of all the datatypes being uniqueidentifier most are varchar(50) and some varchar(100). Fields are true GUID some where created by ...
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1answer
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Relation that combines entries with their subsequent entries, in order of date

I need to come up with a query that can do the following: I have a table with a bunch of transaction records, whose attributes are not important, other than the attribute Date. I need to come up ...
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74 views

Data modelling concepts

Let´s say I have 3 entities. Can I have them all linked to each other "forming a circle" where each one is linked to the other trough a many to many relationship. Cheers
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Can relationships have relationships?

I have the following requirements (as part of a larger system). In the database, I need to maintain a list of parts, suppliers who sell those parts. Many suppliers can sell the same part and each ...