Category of database management systems characterised by the ability to join two data sets by matching on common fields, using mathematics-based relational logic.

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Suitable schema to record email sent and response received and invoicing in DB

When a form submission is made on a website: An email with form's details is sent to a set of recipients email addresses stored in a DB. The email contains a link for the recipient to show interest. ...
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2answers
302 views

Should I use a compound or surrogate PK in a many-to-many table?

I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` VARCHAR(255) NULL DEFAULT NULL, PRIMARY KEY (`isbn`) ) COMMENT 'Books used at this ...
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106 views

Table with multiple lookups

I bet this may be a duplicate and I'm not forming the question correctly, so feel free to point me in the right direction. Background We have a SQL Server with some legacy data. They're all ...
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1answer
72 views

Create one-to-many to two fields in different table

I have a database where I am trying to figure out how to join a table that contains an object called ModelType. The calibration table contains two fields (EffModel and BkgModel) that are based on a ...
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163 views

MongoDB/MySQL - auto increment vs object ID

I am in the process of evaluating MongoDB and writing some basic PHP applications around it. Typically in my PHP/MySQL applications, I would create an ID field and set it to auto-increment on each row ...
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13 views

Medical History - Is this DB properly design?

Could you please tell me if this DB is properly design? Are relationships type correct? Is there anything I should delete or add? Thanks you all very much!
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35 views

Database schema design for individual configurations

I'm trying to design a database schema that allows me to store customer custom built products. As a simplified example: A user can buy a cupboard, draws, boxes, and dividers. A cupboard has 2 tiers. ...
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173 views

Multiple relationships between the same entities

Is there a name for when 2 entities can have multiple relationships between them?
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28 views

Help with relational database design

I have a data model where each user profile belongs to a department. Each job is also available for a specific department. The department names are formatted like this: AAA-BBB-CCC-DDD-EEE, but of ...
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76 views

Transforming table to third normal form

I have a table like this: L(A, B, C, D, E) and functional dependencies are: AB -> CDE C -> D D -> B D -> E I need to transform this table into 3NF. I think it's not even in 2NF. I ...
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1answer
73 views

If A and B are candidate keys, then AB is candidate key or not ?

If R{abc} is a relation, f{ a->b b->a a->c b->c }, then a and b are candidate keys. What about ab ? Is it a candidate key or is it a super key or both ?
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2answers
136 views

Logical problem with a database model

Beforehand the table names and columns are in Spanish, my native language is Spanish. (table names have been now edited to English) I've got a database to manage the tickets sales of a trip that is ...
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820 views

How to insert values into a table from two different tables?

I have three tables students table ------------------------------------ id(PK, A_I) | student_name | nationality teachers table ------------------------------------ id(PK, A_I) | teacher_name ...
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34 views

MySQL Query Causing Massive Slowdown Over Time

I've been experiencing massive slowdown on my server after launching a new website. Using MONyog I can see that after an apache/mysql restart, the queries/second starts out nice and low for around 10 ...
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19 views

Database systems with users and sub users accessing the data

I am making a database for school student maintenance. Below is the basic description. There are schools. One school has many staff (i.e: Principles,Teachers, Section Head, Office Staff etc) These ...
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30 views

Designing a correct table structure

We are trying to save the Family History of a particular foreign job applicant. Below are the details we have to save. Familiy Member: Father|Mother|1st Brother| 2nd Brother| 1st Sister| etc etc ...
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21 views

How to have a relation applied only to all entities related to another given entity?

Let's say I'm trying to design an online server for judging a bunch of submissions to several problems. Firstly, each problem has many subtasks (which must go to one problem alone). For each ...
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1answer
62 views

What's the best database if i want save data temporally? [closed]

I want to create a datalog system so I need to store some int data temporally. What would be the best database (Relational, NO-SQL or some specific) for that purpose? And what would be the best way to ...
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24 views

In terms of relational databases is a Relvar the equivalent to a Schema?

I've been reading up on relational databases and the term Relvar and schema keeps coming up. From my understanding: A relvar is a variable holding a relation. A schema is a logical definition of a ...
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57 views

How to design a Many to Many relationship table?

I'm new to DB's, so I'm not really sure how to even formulate the question. Please feel free to edit the question itself. Anyways, let's describe! I should advise that I am using MS-ACCESS for this ...
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0answers
68 views

Storing URLs in a database

I am thinking about storing URL's in my database, but I am not sure whether the way I use is an efficient way to do things or not. Table name : url url_id (Primary Key & Auto Increment) url_value ...
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0answers
36 views

What are the different types of binary relationship types?

I'm new to databases and while studying questions on it, I've come across one that I can't find the answer to. Define the three different binary relationship types that are common in relational ...
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1answer
61 views

How to insert values into a junction table?

I add values into my two tables using the code below, but I also have a junction table called book_main_cover and I want to add data into this table to make a connection between book_id and ...
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1answer
19 views

Relation between tables [closed]

This question may be too easy to ask, but I can't understand how to do it. I am new in SQL. I have two tables. Table I book_id (AI & Primary Key) book_name book_year Table ...
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274 views

Create relationship between two tables with composite primary key

I've created a table [t1] with two fields and a composite primary key, show in below: create table t1( id int, name nchar(10), primary key(id,name) ); I want to create a second table ...
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2answers
69 views

SQL Query: Selecting a person who is a member of all existing groups

I'm tinkering around with my very first SQL queries and am completely baffled by a problem I encountered. Let's say I have the following database: PERSON(PID, Name) MEMBER(PID, GroupID) How would ...
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19 views

reports on history table

Assume Trucks which travel between Cityies. I store the Cityies that a Truck has traveled to in TruckLocationHistory table, if the Truck is passing the City, State = Passed and if it gonna stays for ...
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1answer
176 views

MongoDB Manual References vs DBREF

I've been researching MongoDB and trying to see if it would be a fit for my company's product catalog. I came across database references: http://docs.mongodb.org/manual/reference/database-references/ ...
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1answer
31 views

Help with preventing double bookings with variable lengths

I'm designing a sample database for a venue where members can create bookings for venues. I'm looking for a method to prevent double bookings (possibly by creating a button on a form that checks ...
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3answers
92 views

Database Design for Paper Submission System

I am learner of Database design, I want to design a database for a journal paper submission system in which one paper can be submitted by one or more author. I have initially two tables Author and ...
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24 views

calculating Canonical covers

Given F = {AB -> C, A -> BC, B-> A}, compute Fc AB-> C is A extra? {B->C, A-> BC, B->A} 1st possible Fc = {A->BC, B->AC} AB-> C is B extra? {A->C, A->BC, B->A) 2nd possible Fc = {A->BC, ...
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45 views

Help writing the following query to relational algebra

Can someone help me in writing the following query to relational algebra, I am studying DBMS and I am stuck on this exercise. Query: SELECT a.name, d.name. d.grade FROM student a, enrolled i, class ...
2
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1answer
75 views

Inheritance or lot of relationship?

I have to transpose a class Diagram into a Physical Data Model (more precisely MySQL database structure). In my class diagram, I have a lot of entities (A, B, C, D) which inherit from an other ...
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310 views

How to insert values in junction table for many to many relationships?

I have three tables in database: trips(trip_id(pk), trip_name(unique), user_id(fk)) places(place_id(pk), place_name(unique)) trips_places_asc(trip_id(fk), place_id(fk)) Since, many trips can ...
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2answers
53 views

Need help about giving relationships in database design

I am developing a simple blog application in which users can write posts and others can like, comment, share etc. i am facing difficulty in designing database. What I have tried is: user ...
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1answer
69 views

Trying to map postal codes to their respective cities, but running into some issues

The Problem I am creating a database of Countries, Regions, Cities and Postal Codes. Here's an example to give an idea of the database structure as it is now: Now, let's take Tuskegee University ...
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1answer
43 views

Transforming a relation to 3NF

I'm trying to transform the following relation to 3NF but can't figure it out. The relation is (a student can only have 1 major): STUDENT (StuID, StuName, Major), Primary Key = {StuID} I tried the ...
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3answers
50 views

Study material for Advanced Databases module inc SQL, Relational Model, ERM & TM [closed]

For my next module in my masters, I am planning on studying Advanced Databases. (Long story short, the masters is designed for people with NON-CS degrees, so I have never studied databases, therefore ...
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1answer
84 views

A question regarding the performance of normalization

I am sorry this is such a newb question, but it is one thing I am having a difficult time wrapping my mind around, and after an evening spent reading I finally just decided to ask for some ...
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3answers
482 views

Replace relational database with “poor” design in software product with non-relational DB? [closed]

Edit: This question is about how to deal with many issues that arose from a overall system design, which made parts of the system deviate from common standards. For example, managing everything in the ...
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45 views

Multi-Tiered Database Design Issue

I am trying to build the multi-level model as demonstrated. When a user creates a campaign they will select some categories and some metros from tables Category and Metro. Those selections will then ...
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1answer
54 views

Is using a relational DB for storing votes and (accessed resources) overkill?

I am writing a forum component for a site and would like to keep track of what topics/questions a user accesses so that other topics/questions can be recommended based on said users previous choices. ...
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2answers
369 views

Advanced search engine or server for relational database

In my current project we are storing big volume of data in relational database. One of the recent key requirements is to enrich application by adding some advanced search capabilities. In the Project ...
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2answers
193 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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27 views

Employee permissions in ER model

I'd like to model an approach to permissions which I can visualise in code but am a little blurry about on the ER side of things; Each user will be logged in at this point and bound to a record ...
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1answer
39 views

Modeling global and private parameters

I'm trying to model a database that will be used for management and execution of SSIS packages. The entities are Client, Job and Package. A Job is the managed unit that references Client and Package. ...
2
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1answer
31 views

Is it possible to enforce a Unique Constraint on a Dataset comprised of joins

I am playing around with an idea to describe friendships in a system, and I am wondering about constraints. I currently have a database that looks like this: Users: ...
2
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0answers
2k views

Schema for an RBAC (Role-based Access Control System)

I want to implement an RBAC, Flat based. I've decided to base my system on the NIST standardization model. Although all fine and well, I have an inclusion to that design. Instead of a hierarchy ...
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4k views

Designing a user authenication (Roles & Rights) module

I am trying to model a User Authentication module for a MS SQL Server database that will be the back end to a Delphi UI Application. Basically, I want to have user accounts where the user belongs to ...
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3answers
65 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 ...