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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Single or multiple databases?

I am in the progress of designing a database (or databases) for somebody and since I am a beginner I would love some advice. The data is described as: Customer1 (c1.type1, c1.type2, c1.type3) ...
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80 views

Decorating an existing database table with information that no one else cares about

We have a table that many processes read from. Some of them want to keep track of the fact they have processed this data, whereas others simply rely on fetching the data from the table based on user ...
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125 views

Where do caching servers conceptually fit in my architecture?

Given the simple well-known architecture below: Where (conceptually) does the caching server(s) sit?
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176 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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1answer
236 views

Guidance on simplifying the following diagram

I have a case scenario where a customer can book accommodation or flight only or both. I have modeled the accommodation part, however i am making things complex by over-thinking how stuff works in ...
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618 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 ...
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4k views

Set permissions on all objects for SQL users

I have a procedure that loops through all objects in the database and assigns them proper permissions to that object. I want to know if there is a better way to do this? I use a model database to ...
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456 views

Determining sizes for Separated Partitions of programs, data and logs in SQL Server

As per the recommendations of the CIS benchmarks for SQL Server, I want to create separate partitions for the data, the programs and the logs on my SQL Server dedicated server. Question is, what is ...
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1answer
182 views

In a recruiting website, should I force a choice between one table for jobseekers and employers or 2 separate tables?

I'm working on a recruiting web site and I was wondering what would be best between: 1) A User table, the employer accounts are linked to a company (therefore when companyID is null then it's a job ...
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55 views

SQL Server 2012: set a column to only use a single case?

Is there a way to tell SQL Server 2012 to store both A and a as A (or both A and a as a) for some given column such that every insert statement does not need to have UPPER() in it?
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67 views

Copy table with separate sequences for serial columns

While creating a column management tool I came across the need to quickly replicate tables in PostgreSQL so I would not test new tools with non-test tables. To effectively test the new column tool ...
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35 views

Optimal indexing for SELECT (mysql)

What indexes would you recommend for the following select (and why)? Keep in mind there can be tens of millions of rows. SELECT * FROM mytable WHERE md5 = ? AND created_at >= ? AND created_at ...
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1answer
115 views

one table for all blob with a one to one table for metadata which link to one or many tables?

I'm going to start by saying that I'm not a DBA but i got that role in my current project so I'm doing my best. The application must be able to store files(attachments, official documents, etc) The ...
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71 views

Composite Foreign key to single primary key [duplicate]

How do I create a composite foreign key to a table with a single primary key? For example suppose I have the following tables: CREATE TABLE Branches ( BranchId UniqueIdentifier DEFAULT ...
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80 views

Unique column values between tables

I'm keeping track of teams and their members. Each team has one leader, one contact person, and any number of players, and each of them has a unique email address. The problem is that one physical ...
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195 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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1answer
46 views

Building dependence between regional data (Street -> City -> PostalCode -> Country)

I'm in the process of designing a database to contain regional data to be used inside a CRM system. So, a user suspects that things like the city or country are automatically filled (or maybe just ...
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3answers
67 views

Best approach for Legal/Natural can have many Orders

I'm working on this model: where as you may see one NaturalPerson can have many Order and the same for LegalPerson the only difference between NaturalPerson and LegalPerson are a few so in that ...
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184 views

Relational Database design best practice

I am a student and I am trying to design a simple database, so if the ideas seem bad please let me know how to improve. I have three tables in my mind, one for Professors and one for Students. Both ...
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1answer
82 views

Should I use a surrogate key in a mapping table?

I am deploying a mapping table which connects Items to ItemGroups Though an Item will only ever be in a single ItemGroup please accept a priori it is not appropriate in my use case to append a column ...
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79 views

How to store list of unknown size in database

I have trouble with database design and don't know how to overcome this. The problem is with list of cities between two chosen city. User chooses start and finish city, and OPTIONALLY, user can write ...
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121 views

Is my ERD valid for airports,cities and airlines database?

My objective is to make a database of airports, cities and the airlines which provide coverage to them. I asked the question before on stackoverflow and the person told me to break up the ...
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1answer
28 views

Duplicate Data from two column

i have a table which has only two column one is pid(Photo ID) and another one is tid(Tag ID) +-------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | ...
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6answers
2k views

Efficiently storing irregular/repeating intervals (think calendar/events)

I am developing a service that relies on users being able to recieve messages that they themselves choose. These messages need to be stored somewhere before they are send for processing. Right now ...
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104 views

Confusion with Foreign Keys

I've been tasked to build a somewhat basic Prisoner database and I've run into a situation where I don't know what the appropriate route to take is. I have a Prisoner table, that looks like the ...
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111 views

Best approach on storing/displaying sanitized data

Surfing the web I find two approaches on storing data in databases. Approach 1: Store data in the database with the html-specialcharacters sanitized $userdata = $_POST['field']; ...
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Source control makes sure my code is never lost, how do I make sure my users/orders database is never lost?

Everyone is recommending the use of git, automated tests, continuous integration, automated deployment and so on, to reduce human error during all stages of web development. I have yet to come across ...
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67 views

Better way to manage data integrity, without having too many composite FK's

I have following tables: class_table (class_id = Auto Incremented Primary Key (AIPK) of this table) user_table (class_id, user_id (AIPK of this table)) course_table(class_id, course_id (AIPK of this ...
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54 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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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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251 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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978 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
556 views

Add a column contains a photo

I installed PostgreSQL 9.1 under Ubuntu 12.10 And now I have a table called property I want to add a field that can be used to store photo(link to the photo or import a photo into a column?) But I ...
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264 views

User Table Design

I am designing for an ecommerce application, I need to know how to implement the following task. There are 2 options, Unregistered Users (Free Listing). Registered Users. In this the unregistered ...
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1answer
263 views

Design DB for users with different information fields?

Let's say I want to register all faculty of a university and they are in different fields and have different resume information. Here we have some common fields and some field specific fields. for ...
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809 views

Database Design for lookup tables

I have a transaction table called questionnaire and a question lookup table called question_codes. questionnaire qst_id - number (primary key) question_type - number (foreign key) ...
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1answer
143 views

How to link a customer to a country when the city/state isn't known

We have a situation where medical systems are sold to hospital groups, but at the time of the order, we don't always know into which state and city the system will be installed. We always know the ...
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1answer
758 views

Need advice for table design for multi-user access

I have an inventory application that needs to support multi-user. As of right now, only one user can access and manage their items. I've gotten a lot of requests to support multiple users so they can ...
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952 views

boolean purpose column char(0) or tinyint(1)

For Boolean purpose column which one is better: nullable char(0) or tinyint(1). I know bool is an alias for tinyint(1) , but in "High Performance MySQL" book that published by O'reilly said: "If ...
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61 views

Can a database detect that data is out of sequence if each datapoint has a sequential ID

Can a database detect that data is out of sequence if each datapoint has a sequential ID? E.G A trading DB server receives trade ID 9, and next receives trade ID 11. In this case, I would like the DB ...
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363 views

How should I store multiple relationships (many posts to many categories)?

I have posts stored in a posts table and I want each post to have multiple categories, what is the most efficient way to store the categories and their relationships ? I thought of it this way first: ...
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1answer
100 views

Approach for a 2,000 table migration

What might be the best approach when converting or migrating a database containing over 2,000 tables? Where would you begin to tackle such an issue? Steps to take in the first weeks of designing? ...
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1answer
51 views

Adding users to a list and sort by category?

I'm using SQL-Server 2012 and I would like to know how to solve this program. So: I want to create a page that allows admins to manage a project, and part of it, would be to add members/employees to ...
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139 views

Handling expiration in a course registration or ticketing system

I want to restructure the database for a web application I inherited for handling summer camp registrations, but my question is relevant to any event registration or ticketing system. My question is ...
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298 views

Refactoring/normalization - but almost empty table

I normalized a legacy DB into this structure: But I'm not sure if it is correctly normalized. I don't feel very comfortable with the almost empty filters table. The requirements A group contains ...
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371 views

Database Design question, calculate or save financial positions

As the question states i'm currently internally strugling witha database design question. I work as a software developer (and i tend to do everything database related aswell since we're rather small) ...
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6k views

Multiple parents and multiple children in product categories

I am making a ecommerce site. In this site I want to categorise the items into three different layers primary category sub category sub category >>electronic ...
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2answers
236 views

XML Large DataBase is the best? [closed]

Is the best way to implement a large database is XML? Or is there a better way? 1 - reduce the time complexity 2 - Reduce the amount of traffic between the tables And other factors ... Which ...
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395 views

DB stored procedures: how do they help increase security in web systems?

The usage of Oracle PL/SQL procedures for controlling data access is often emphasized in PL/SQL books and other sources as being more secure approach. I'v seen several systems where all business logic ...
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138 views

a question in tables relations

Table A is linked to Table B , and Table B is linked to Table C using primary and foreign keys My questions: Should i link Table A to Table C too?? Or Table B can act as intermediate link between ...