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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In mySQL possible to change auto-increment ids that have huge gaps and if so how?

I am importing a 50 table relational database (I'm not a dba) with 250,000+ records in most of the tables, yet the auto increment is off in most tables, some for example showing the last ID at 5 ...
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1answer
576 views

Advantages of middle tables in one-to-many relationships

Entities: Lists Leads What I am trying to achieve is a scenerio where in the relationship between lists and leads the following constraint is applied: A list can have many leads, but a lead can ...
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1answer
27 views

Good idea to include summary of frequently accessed data from another foreign-keyed table?

Sorry for poor title, I'll try to explain it in more detail here. I have an application that often gets a row from table A, then looks up a column from that in a foreign key mapping table (table B), ...
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2answers
134 views

Multiple relationships issue

Here is my SQLFiddle: http://sqlfiddle.com/#!2/affc4/9 A brief description of the issue: I have the following data: topics brands celebrities All 3 of those data types can be associated to an ...
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2answers
2k views

Diffrence between relational and unrelational database [closed]

What is the difference between relational(MySql) and unrelational database(MongoDb)
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97 views

Need advice on this EER Diagram

This db will work with a CakePhp app and need advice about design. Is it good idea to put orders on center or should I put clients on center? Clients has orders and an order record can only have one ...
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2answers
84 views

Several stays: many-to-many relationship

Could you please help me with the following problem? I'm a total novice in DB design. I have a table with researchers who visit our university. They come for some period of time (from, till). Now, ...
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0answers
64 views

Table Structure: 2 Related Entities Share the Same Entity

I was hoping I could get some advice on my table structure. Im writing a simple workout tracker for me and my buddies. These are the requirements: Multiple users A user can have multiple workouts A ...
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1answer
423 views

Event Management System

I'm working on a "Event Management System" Online Software Project where the system requires the following: Viewers can sign up for their user account Events can be created by the admin from the ...
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589 views

The nature of the relationship between two tables in MySQL

Good day. I'm designing a database for a research project where we're predicting whether or not young female athletes will rupture their ACL(s) based on the nature of a test jump recorded with a ...
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1answer
700 views

What does a round relationship icon mean in MySQL Workbench Visual Data Model

I have created a model in the Visual Data Model of MySQL Workbench, and on one single relationship, this icon shows up: What does it mean? The Relation is 1:1, and this icon shows only on this ...
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2answers
143 views

Is there any way to tell the number of matches found in a database value matched with LIKE?

Is there any way I can query a SQL-Server-CE database that will return the number of matches found in a cell value using LIKE (or MATCH AGAINST or any other method I'm not aware of, really)? EXAMPLE ...
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2answers
32 views

Help wrapping my mind around many-to-many relationships

I'm making a database that needs to have the following tables: Article, Video, Image, and Keyword. Keyword contains a fixed list of keywords. (For example when creating an article, you'd have to ...
2
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1answer
33 views

NEWB Getting to KNow New Database and Understand Where Relationships Are

I'm teaching myself SQL using MYSQL and a textbook. While working through the textbook I'm using a database I'm kinda familiar with - an exported copy of my CMS driven websites database. My website ...
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1answer
31 views

related column contents

I've designed a mysql database made of several independent/unrelated tables to use in my office. Different tables hold information about clients (names, addresses etc), visits to the office (dates, ...
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1answer
49 views

Bit column vs multiple join tables

I asked a question earlier about how I could define a many to many relationship between users and FOSes (fields of study). My original question was how could we know whether the user was the ...
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1answer
243 views

Multiple junction tables?

I am working on a system where you have users, and you have Fields of Study or 'fos' for short. Each user can have many fos and each fos can have many users. So we are dealing with a many to many ...
1
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1answer
48 views

JOIN to read first table and get possible relationship in the second table

Consider a main table as CREATE TABLE groups ( group_id int(11) NOT NULL AUTO_INCREMENT, group_title varchar(255), PRIMARY KEY(group_id) ) ENGINE=InnoDB and a second table for relationship as ...
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1answer
120 views

How would I change this relational model to fit a nosql database?

Because of things beyond my control, I have to switch from a relational database to MongoDB for the advertising platform I'm helping to build. I've got a relational schema sketched out, but I'm unsure ...
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1answer
2k views

Candidate key = Key = Minimal Superkey?

I got a little confused by all these keys. As I understand A key of a relational schema = The minimal subset of a superkey that is still a key = A candidate key Is this correct or not?
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1answer
90 views

Index optimization

I'm building a 'tag' system for my blog posts. Currently my tags table has columns tagid - MEDIUMINT NOT NULL AUTO_INCREMENT PRIMARY KEY and tag VARCHAR(30) NOT NULL UNIQUE. And I have another table ...
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1answer
198 views

Separating tables vs having one table

At the moment I have a table setup that looks somewhat like this: create table tbl_locationcollections ( id int(11) PRIMARY KEY IDENTITY, --(Primary Key), name varchar(100) not null, ...
0
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1answer
172 views

Is it better to use multiple one-to-many relationships, or polymorphic?

I've got the following tables: Clicks table Websites table Ads table Both Ads and Websites have many Clicks (i.e. both models have a one-to-many relation with Clicks). In such cases, is it better ...
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1answer
264 views

Switching to NoSQL for native JSON use?

I am rather comfortable writing concrete schemas with explicit primary keys, foreign keys, indexes, views and stored procedures. For queuing I use a NoSQL solution called: Redis. Recently I heard a ...
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0answers
255 views

Use cases for NoSQL databases: Time series

I need to set up a database that will record temporal series data (sensors). A friend of mine has recommended me to use a NoSQL database instead of using Oracle (for instance). There're also some ...
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1answer
413 views

Delete entry from related tables

I can not use InnoDB engine because of some dependency troubles in LuaSQL and PtokaX. My current query is something like: DELETE e.*, m.* FROM entries e INNER JOIN magnets m ON m.eid = ...
2
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1answer
267 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 ...
3
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2answers
304 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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1answer
446 views

Record with variable number of columns?

I am trying to model a cable mapping for devices. Each device has multiple cards, and each of those cards has multiple ports. Since both the number of cards and ports vary, I am confused on how to ...
2
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1answer
1k views

Modeling a ticket system based on a set of disparate kinds of tickets?

I'm working on a project that allows for the creation of "support tickets." These are not confined to something that needs fixing, however, so in a way they could more accurately be called "jobs." ...
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1answer
178 views

What is the real-world purpose of an optional 1:1 relationship?

I know that one-to-one relationships can be used to split data into multiple tables for performance or security and that it is used to create a is-a-relationsship. But aside from that things, what is ...
7
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2answers
527 views

Best relational database structure for this data

I'm in the process of creating a database scheme for the following scenario: There are users Users have roles (such as "Developer" or "CEO") Roles have applications (such as "Topdesk") Applications ...
2
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3answers
974 views

Database Design Relationship for Patient Visit in MS Access

I am designing a database to store records for research purposes, and I am having trouble picturing how I can create a relational database based on the information I have. There are a total of 6 ...
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4answers
391 views

Arbitrarily ordering records in a table

A common need when using a database is to access records in order. For example, if I have a blog, I want to be able to reorder my blog posts in arbitrary order. These entries often have lots of ...
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0answers
55 views

Create Scheme that allows for fluidity between entities [closed]

We are a small rapidly evolving company and recently investigated switching databases from SQL Server to a graph database. We like the graph approach because of the fluidity and openness that it ...
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1answer
280 views

Database Relational Design for Multiple Categories

I am building a database for participants who are grouped into studies. There's a total of 5 different studies - A, B, C, D, and E. The participants may be in more than one studies, and participants ...
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1answer
58 views

Correct data model for users with clients

I have an application where users are granted access. Part of the system allows users to have their own 'clients'. I have a users table ******************************** users ...
8
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3answers
5k views

How to have a one-to-many relationship with a privileged child?

I want to have a one-to-many relationship in which for each parent, one or zero of the children is marked as a “favorite.” However, not every parent will have a child. (Think of the parents as ...
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1answer
98 views

Looking for a scalable relational database [closed]

I'm looking for a database that achieves the following: fully ACID. relational with joins. has transactions. allows the administrator to specify sharding rules (for example: users from Europe should ...
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2answers
427 views

Relationships in a school database

I am designing database for a school app. Student is the main entity in the database. Student has relation with Parent & Guardian. I am confused as where to store references. As will student ...
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1answer
583 views

SQL Server 2008 - How would I create a dynamic query for finding relationships and references to the primary key?

Since I'm new and I've never shared, and yet there are a few useful scripts that I need on a daily basis, I thought I should. As a new DBA, some data fix DML operations and simple business logical ...
3
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1answer
147 views

Optimised Schema for City-to-City Distance Table

This is my first question, forgive me if this question is simple. I'm stuck here, trying to implement the relations for the data represented below. I want to scale it vertically (new rows), instead of ...
1
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1answer
119 views

Relation candidate keys

I have the following relation: R = ABCDE F: AB->DE, AC->B, DE->C, AE->C, C->AB I need to determine this relations candidate keys. Now, if I understood the defintion correctly: ...
4
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1answer
279 views

How should I model a worflow of status/activities ? (rules like “if is 3 go to 4, if is 4 go to 5” etc)

I'm trying to model a workflow (status and activities) to create "rules". Let me give you an example. The main "object" let's say are "vehicle requirements", I will have this table: idRequirement, ...
1
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1answer
116 views

Can I place the attribute in the Entity, when the foreign key is also already present?

I am using DBdesigner Fork for generating ER diagram. I have the 'Company' as an entity for which can I place the attribute of 'idShares', despite of having the foreign key of Shares Entity in the ...
2
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2answers
1k views

Database Design - One table for different types of transactions

Considering a procurement system as an example. Would it make sense to have one single table for the following: Quote, Order, Invoice and Credit Memo? There will be some details that are different. ...
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2answers
66 views

View for a MANY_MANY_MANY relationship

Let's say I have 3 main tables: category, tag, url category and tag have a MANY_MANY relationship (category_tag). tag and url have a MANY_MANY relationship (url_tag). I would like for a given ...
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2answers
104 views

Table Design - Identical tables for different statuses

I am developing a transactional System and the below is a simplified scenario of my problem. Users enter JOBS in a system. A User first enters a JOBS with a DRAFT status (and the Job is given a ...
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1answer
1k views

How to model entities in an entity relationship diagram?

I'm a beginner Database designer and wondering if anyone can help me understand this. Let's say we want to design a system that has, among other entities, an entity called Vehicle, and another one ...
3
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1answer
510 views

Applying user-defined fields to arbitrary entities

Currently we have an old (rather crude) system that has user-defined fields, which are mapped against rows in arbitrary tables. This was an after-the-fact modification based on a customer request, and ...