Entity Relationship Diagram

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2
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1answer
211 views

Help with a scenario of music groups and members in ERD design

Can someone please show me how to construct this ER diagram with the following scenario? I’m confused with the ‘or’ part of it. Description An Artist has a Name, and must be either a Group or a ...
5
votes
1answer
15k views

How can I import the contents of an Oracle database into Visio to create an Entity Relationship Diagram?

I have an Oracle database, and I would like to create an ERD in Visio 2007 Pro. I have so far looked at DBMS_METADATA.GET_DDL commands to generate DDL. I know that I can import an Access DB into ...
0
votes
2answers
952 views

SQL - Cannot Add Foreign Key Constraint

Can anyone tell me why there are errors such as : Cannot Add Foreign Key Constraint And am i on the right track ? DROP DATABASE technology_university_hospital; CREATE DATABASE ...
0
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0answers
36 views

ERD diagram for online ticket reservation system [closed]

Simply, the problem is about to create sale and reservation system for bus transport company. The biggest challenge is to design database that it will be prepared to situation like this: The bus ...
0
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1answer
23 views

Issue with forming correct relationship between subtype and another table in ERD

The focus is on the Cashier table and the Cash Accountability table. The rule is that only Cashiers have Cash Accountability and a Cashier ideally only cashes out once per day. Before I changed the ER ...
1
vote
1answer
41 views

Bicycle Sharing Scheme - ER Diagram

Please compare the directions below to my ER Diagram and tell me if anything is wrong with my ER Diagram Please I think its accurate enough. Oxford City Council is preparing to launch an innovative ...
0
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1answer
58 views

Does my ERD look well designed?

I am making a database at no cost for a local dance school. I'm still very new this would like to be sure that I designed it appropriately. From the front end, the parent will: fill out their ...
0
votes
1answer
51 views

Database Design / ER Diagram - Help Needed

Please take a look at this ER Diagram that I started. I just don't know if I've set it up correctly (I have not made any relationships yet). I just want to know if I have the appropriate "Tables" or ...
0
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0answers
55 views

ER Diagram Issues

I'm currently working on a project and I just can't figure out how to setup the portion in "BOLD" and any help will be greatly appreciated. Oxford City Council is preparing to launch an innovative ...
5
votes
3answers
1k views

Are there any tools to go from ERD to DB design and vice versa? [closed]

I'm learning DB design and looking for some tools, preferably open source software, that could help go from an ERD to a DATABASE and vice versa. For the record, the database i'm using is MySQL.
0
votes
2answers
43 views

Does an empty entity make any sense in an entity-relationship diagram?

I have an entity that has nothing else than a surrogate key as a primary key. I use it as an element made of a group of other elements For example : TABLE SchoolClass (classNumber INTEGER ...
1
vote
1answer
51 views

How to get a surrogate key value in order to put a foreign key in and create relationship?

I am trying to create two relationships between three tables, using foreign keys with values of primary keys, which are surrogate keys. But I don't understand how to enter the right value in the ...
0
votes
1answer
30 views

middle table in one-to-many relationships

I just started using mysql workbench but it is slightly from the er diagram that i design in paper. I want to have a 1 to many relationship with three tables. For example a have entity A and entity B ...
0
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2answers
28 views

ERD Design for Campground and Campsite

I am designing erd for campground and campsite. In general, a campground has many campsites in it. that lead to one to many relationships. but sometimes campsite has no campground, it appears as the ...
0
votes
1answer
160 views

Is an ER diagram an example of a conceptual, logical or physical schema?

I have been reading databases, and I clearly understand the difference between a conceptual, logical and physical schema. An ER diagram is an example of which of these schema's?
0
votes
1answer
56 views

How to model IsA in an ERD with crow's foot notation

For an assignment I have to create an ERD. I am doing this in Lucidchart using the crow's foot notation. There is however one thing I cannot figure out, how would you present a IsA hierarchy in crow's ...
0
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0answers
11 views

Is the use of my lookup table efficient?

I'm trying to find the best way to architect the relationship in the scenario that: A team can have multiple players, a player may also have multiple teams My first thought was to use a lookup ...
0
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0answers
34 views

ERD to data structure

I'm new to databases. I converted my ERD to data structure. Althougt I made sure all the 1NF, 2NF and 3NF are handled, I'm skeptic about it. This is the data structure. Port(PortID(pk), Name, ...
0
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0answers
9 views

Identification of other entities.

Given the following scenario, what three other entities (and their attributes) would be of importance to this model? SCENARIO: The transport authority in Jamaica has recently added train ...
1
vote
2answers
103 views

New to databases - does my ERD reflect good database design?

I'm making a database to hold data for a media player that I'm working on. Originally, I thought to use one table with the fields: {filePath,artist,title,album,track_number,length,date,artworkUrl} ...
0
votes
1answer
37 views

How to define User/Permission relationship as M:M?

The Resource relates to Action as M:M via Permission join table/separate entity. User can have many permissions. The same permission may be assigned to multiple users. How to define User-Permission ...
0
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1answer
37 views

Relationship issue

I'm working on a ERD with mysql workbench, and i have a little question. I have a Database with this tables: company_address country state city I want to store the address of the company with all ...
0
votes
1answer
93 views

What is the best way to represent an album and song entity in an e-commerce schema?

I'm designing a simple mp3(music) ecommerce site, customers can either buy a single Track or whole Album, an Album is made up of Tracks, so there is a one to many relationship between an Album and a ...
2
votes
1answer
36 views

Database table to keep track of objects

I have a table called FoodMaker and another table called Settings. Every FoodMaker has multiple Settings. I also need a 3rd table to record what has been made, when and with what Settings. It might ...
1
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1answer
28 views

Financial Inst - Model Role+Relationships b/w Person and Account

A Person can be on one-or-more Accounts. For each Account a Person is on, Person has a certain role on that account i.e. Person 1 is primary on Account 1 Person 1 is joint on Account 2 Person 1 is ...
1
vote
3answers
340 views

Database design: 4 types of users but have different functionality , separate or one table?

I have 4 types of users: Admins , normal user , company , service provider Admins and normal user share some attributes (id .first name ,last name ,phone ,mail) company and service provider share ...
0
votes
1answer
90 views

ERD Design for Employee Leave

I found the following ERD design: Which trying to capture as much information about employee leave (i.e sick, travel, etc). What am trying to understand is what does the columns: Table : ...
1
vote
2answers
103 views

What would the relational diagram look like in this situation?

Situation Last week I had to do an assignment, and I did not agree with my teacher's ERD. She used a n-ary relationship while I used two binary relationships. I would like to know a true dba's (you) ...
0
votes
1answer
90 views

When to use a multidimensional relationship in an ERD?

When to use a multidimensional relationship in an ERD? My textbook is in Dutch, and the two paragraphs that explain about multidimensional relationships is too vague and brief. I don't understand when ...
0
votes
1answer
54 views

ERDs and modelling ownership of roles within Job table

I'm currently in the process of modelling what I see as a relatively simple relationship through my ERD. I'm not even certain that strictly speaking this is Many-to-Many but nevertheless there ...
0
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0answers
32 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 ...
0
votes
3answers
322 views

Completion of ERD, uncertainties about generalization/specialization and primary keys

I'm practicing making conceptual databases and I would like to know of I'm on the right track. I've been trying to create an ERD for a scenario as follows: A hotel can take bookings for weddings, ...
0
votes
0answers
32 views

Completion of ERD, uncertainties about generalization/specialization and primary keys [duplicate]

I'm practicing making conceptual databases and I would like to know of I'm on the right track. I've been trying to create an ERD for a scenario as follows: A hotel can take bookings for weddings, ...
0
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0answers
16 views

How to model mappings at various levels

I'm trying to design the database model for my application and I'm finding it difficult to design the mappings for user access to various entities stored in the database. If access was only ...
0
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1answer
1k views

Converted ERD into Dependency Diagram 1NF, 3NF

Thats the ERD. I'm studying for an upcoming test and having trouble getting my head around converting thes ERDs into dependency diagrams. This is from a previous exam that the Lecturer told us to ...
2
votes
3answers
205 views

Entity Relationship Model - double one to many

ERD A customer submits one or many leads. A lead belongs to one customer. A lead is a request or an inquiry. A lead belongs to one manufacturer. A manufacturer has one or many leads. Tables ...
2
votes
2answers
3k views

Is it OK to have an entity in an ER diagram without a relationship?

I'm creating an ER diagram for a class assignment and I was wondering if it would be possible to create an entity that had no direct relationship to any other entity, and simply use foreign keys to ...
0
votes
1answer
259 views

Relational Model Design - Entity with one attribute

I am trying to desing a database relational model for an assignment. At first, I design the ER diagram and next the relational model with tables(Schemas). So here's my question : Is it possible for an ...
0
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1answer
130 views

Implementing a simple ERD in MySQL: is the implementation below 100% compliant with the ERD?

ERD Consider the following ERD: Tables From it, I derived the following tables: Company ------------------ c_id c_name ------------------ CompanyEmail ------------------ c_id ...
1
vote
2answers
151 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 ...
0
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1answer
207 views

Conversion of simple ERD to Table: is the solution below any good?

Consider the following ERD: Suppose that all entities only have two attributes: a PK plus a name/number. I want to convert that ERD to tables. Is it needed 4 tables (1 for each relationship ...
1
vote
1answer
661 views

How much the decision to use ternary or binary relationship influences the accuracy of the model with regards to a given business model?

The question title is very long, so here's a little bit of context to (try to) make it clear. I asked a question regarding ternary relationship. The question was Ternary relationship: what's the ...
2
votes
1answer
2k views

Ternary relationship: what's the difference between having single table and having multiple tables?

Consider the following ternary relationship: Suppose that all entities have only two attributes (PK and Name). Here are the tables I derived (5 tables): Sector ------------------------- ...
2
votes
2answers
112 views

Relations between a imeid, sim chip, and account from a cellphone company?

I've never really had a cellphone (that I owned the account to...long story), but at work we have them, and we want to get a series of relations between accounts, devices (mifi's, tablets, ...
4
votes
6answers
30k views

How to export an ER diagram from an Oracle DB?

I am developing this application with an Oracle database. I haven't been documenting the data model, but now an auditor wants to have an entity relationship diagram of my database. There are many ...
0
votes
1answer
188 views

Digital content eCommerce schema advice? [closed]

I don't have much experience designing databases, I'm looking for some advice on my design from more seasoned designers/developers. I'm developing a digital content eCommerce store which will be ...
2
votes
3answers
4k views

Software tool to visualize and print DB diagrams [closed]

I have some SQL Server databases and use SQL Server Management Studio to manage them. However, I find that is not very friendly to create, design and print database diagrams (for existing tables). ...
1
vote
1answer
289 views

Can Anyone please review my database after I did the Normalization ?.Any suggestion is appreciated

User: User_ID,user_name,E-mail Staff: User_ID,Fname,Lname,DOB Student: User_ID fname Lname DOB Lecture: User_ID Admin: User_ID Position ID : P_ID,ROLE_NAME, Staff_position ...
0
votes
3answers
1k views

Db Design of a Room Booking System

I plan on building a web based room booking application for meeting rooms at a company. The requirements are not set in stone and are pretty much left to me, as long as these core ones are met: ...
1
vote
1answer
79 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