Entity Relationship Diagram

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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? My schema looks like this: DDL: DROP DATABASE ...
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1answer
210 views

ERD for a web development company

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...
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1answer
36 views

Store the content book in database, so that it would be updated afterwards or store them as document?

I have some books in (urdu) made with Urdu Inpage(tool for making pages in urdu) like this: problem that these document files are difficult to read in php because they gives unread-able characters, ...
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1answer
36 views

How to represent the optionality of a many-to-one mandatory relationship from the Parent to its two Child entity types in an ERD?

I have a Parent entity type with two Child entities, with a relationship cardinality of many-to-one (or M:1) from Parent to Child. The business rules say that: It is mandatory that the Parent ...
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1answer
51 views

How can I better model the relationships in this project?

I'm developing an internal tool (as an intern). We deal with a lot of hardware, which is all custom and managers have a hard time knowing who is developing on what machine. The three main things to ...
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1answer
98 views

How to add foreign key with more than 1 field in SQL Power Architect

In the picture, I got a model I'm building in SQL Power Architect. I already have table 1 referencing a field (CDCONTR) from table 2. But I want to make the foreign key to reference two fields from ...
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1answer
44 views

ESports League ERD

I'm creating a database for an esports league and am having some issues putting it all together for an ERD. Here's a quick rundown on how the game works: There are 2 teams of 5 Players each. These ...
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1answer
45 views

Should a TeamMembers table have a relationship with the Student Table or the Enrolment Table?

I'll keep it nice and short and simply link to the ERD: Users can be assigned a role, one of those is student. So for the sake of this, Students are the same as Users! A Student can be enrolled in ...
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112 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 ...
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51 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 ...
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ERD for a Contract between a Writer and a Publisher: Is it correct, can it be simpler?

I created an entity-relationship diagram (ERD) for a book publishing business context that I will detail bellow. Entity types The entity types of interest are: Writer Work (as a book) Publisher ...
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ERD to SQL Server

I am working on an assignment and am having one heck of a time getting my head wrapped around these questions. I need to be able to write in SQL Server 2014 certain select statements based solely off ...
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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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Ternary relationship with history tracking

I have the following entities Procedure -> id_procedure , desc_procedure . Status -> id_status , desc_status . Subprocess -> id_subprocess , desc_process . The rules are: 1 ...
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Handling Strong and Weak entity types in a one-to-one relationship

I am modelling a database for a term project and I have come across something I do not have a definite answer to. Diagram I was supplied with the following Entity-Relationship diagram: ...
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0answers
64 views

ERD Diagram based on Crow's Foot model for Milky Way Jewelry

this was on my final exam this past winter exam season, in search for the answer since i got it wrong: Draw an ERD diagram based on the Crow's Foot model for a database to support the basic ...
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126 views

What is a good database design approach for my Online Quiz Android Application?

I have been working on an Android Online Quiz Application with PHP & MySQL. I know what attributes i need however when designing the relationship it becomes complex and confusing when I analysed ...
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0answers
262 views

Quotation and invoice mysql table

I am trying to develop a small business web application for my friends business. I do have some php,html experience so I have done the interface and all. Now I am trying to work on the database. The ...
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What is the correct database design for accommodating a request and a receive transactions?

In my project management system, I have a feature that requests a rental from a supplier. Once the set of equipment arrives, I can now create a rental receive to monitor the equipment inventory which ...
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Database ERD for orders info

I have two tables: 1-orders order_id 2-shipping_and_billing order_id FK address_type(billing and shipping ) city I need to get full info of shipping and billing in single select of ...
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Entity–relationship model and relational model

Entity–relationship model is conceptual model... it defines the conceptual view of a database. It works around real-world entities and the associations among them it is implemented in a ...
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0answers
37 views

Are my two proposed solutions on modelling resources inventory decent?

In the project management system that I am developing, I am wondering what is the best database design for keeping track of the resources inventory. While I want to determine what resources are ...
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ERD question, problem with connecting

So I have a question involving an assignment i got. The question is I can see out of a query the total amount of days a room was occupied. However I think my Reservations and Rooms should be many to ...
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61 views

table design approach for a rental application with several one to many relationships

I'm trying to go about designing a database/tables for the following situation I'm being presented. I'm developing a rental web application with MySQL as db engine. It is for a nonprofit organizations ...
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211 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 ...
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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 ...
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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 ...