FAQ Database Discussion Community


MySQL - Cannot create ERD in Server Instance Schemas

mysql,mysql-workbench,entity-relationship,erd
I am brand new to MySQL and I am trying to understand how it all fits together. I have a very strong understanding of Microsoft Access, but this is a whole new world. I create a schema (MySQL Model) and I had no problem creating an ERD. I then figured...

MYSQL Balance Sheet Design

mysql,foreign-keys,primary-key,entity-relationship,foreign-key-relationship
I'm working on creating an ERD Diagram to map out a MYSQL database. One of my entities in the ERD Diagram is Balance Sheet. How I have it setup right now is: Company PK Company ID Company Name Balance Sheet PK Balance Sheet ID FK Company ID Year Month I...

One to One ER with a Type or Status table instead of a Type or Status column

database,database-design,relational-database,entity-relationship
I have a long way to go with ER modelling, as you'll soon see, but I have a project I'm doing for a construction firm and I'm getting my hands wet with the database model. The company is a roof inspections company and they have projects on sites and proposals...

Entities with a strict 1-2 relationship

database-design,entity-relationship,er-diagram
I am trying to understand how do we model and define the cardinality of two entities when the relationship is of exact nature. Lets say 1 to 2. For an example, if I have entities Journey and Location. Now each journey has 2 locations, a starting location and an ending...

many-to-many relationships with fields in a RESTful API

rest,entity-relationship
I post the same unanswered question from a comment. Let's say I have 2 entities (Team and Player) and a many-to-many relationship (Registration) which have id_team and id_player fields but also others information like registrationDate. GET /teams/{id}/players give me all players of a specific team GET /players/{id}/teams give me all...

Yii: relate n:m on both sides of an AR

php,mysql,yii,entity-relationship
For a better user experience, I didn't want to just make a casual PM system, but actually group it into conversations. And as an added feature, being able to PM multiple people at once. Something that was requested multiple times. So I created this: /* User conversations ONE Conversation HAS...

Is relevant the order of INSERTion in MySQL?

mysql,database,entity-relationship
I have multiple tables, related by multiple foreign keys as in the following example: Chefs(id_chef,name,stars) - where id_chef is the primary key. Recipes(id_recipe,name,calories,category) - id_recipe as PK. Ingredients(id_ing,name,type) - id_ing as PK. Contains(id_chef,id_recipe,quantity,unit) - (id_chef,id_recipe) as PK, and as Foreign Keys for Recipes(id_recipe) and Chefs(id_chef). Autorship(id_chef,id_recipe) - Same as previous....

Use related entity multiple times in query

.net,vb.net,entity-framework,linq-to-entities,entity-relationship
I'm trying to get a list of two tables into one list of a generic class I made. My question is how I could get the fields from the related table without calling firstOrDefault for each field, please see sample code, I need a verly long line for fields Price...

How to set up Primary Keys in a Relation?

database,database-design,relational-database,database-schema,entity-relationship
I wish to know how to correctly set up Primary Keys in a Relation. E.g. we have ER-diagram which contain elements: Key attributes Weak key attributes Identifying relationships Associative entities In order to translate it into Relational Model we should do some tricks. All elements above deal with Primary Keys...

Symfony2: Error “Property was already declared, but it must be declared only once”

symfony2,doctrine,entity-relationship
As I am new to Symfony, I tried creating the entity relationship using Doctrine. I am getting the error Property "report" in "[bundle/entity/file_location" was already declared, but it must be declared only once" when I try to update the schema. I have followed the Symfony documentation, but could not find...

How can i split an ArrayList of Shapes into partitions/lists in Java (Just advice)

java,arrays,arraylist,entity-relationship,shape
I just want an advice or suggestions of how i can do it. i've been thinking about it for hours now and can't find a solution. My aim is to convert this ER Diagram to tables. So i have a Rectangle(Entity) that is linked to an ellipse(Attribute). I've already worked...

how to let user create his own database asp.net website

c#,asp.net,database,entity-relationship
We're building an app where like accountant application online each user is required to have a personal database and I'm trying to find the best way to implement this or I don't know should I put all company data in one database. So far the options are •every company registered...

Listing specific requirements on Access Database form

database,ms-access,access-vba,relational-database,entity-relationship
I am trying to create a database using Microsoft Access Database, but I have a problem. I want to create a database that holds information for computer components and a form to list certain components to build a computer. For example, I want to build computer A, and I have...

Translating ER diagram to Relational model

database,relational-database,entity-relationship,erd
I have a question about the ER diagram below. Question: If there are 2 relationships born and live from actor to place entity. Do they both have the same foreign key which is place_no? So does that mean I just put the foreign key in Actors relational model and that's...

How to detect if entity exist in database

symfony2,doctrine,entity-relationship
I have 2 entities, User and Profile. Profile has in-symfony relation with User, but there is no in-database relation (no foreign key, no cascade) - only simple int column named user_id and nothing more. Problem is obvious: when i delete user - associated profiles persists, but their user_id points to...

The three schema of the database

database,database-design,relational-database,database-schema,entity-relationship
I have created a database in Access and right know i have to write a report. I know that the databasesystem has three forms of schemas: physical, conceptual and external. Does the following ER diagram (by using the method normalization) belongs to the conceptual level?: Or does this belong to...

one account have many friend who have same attribute of user ? how to implement it in DB & how it look like in ER diagram

mysql,database-design,many-to-many,entity-relationship,self-reference
one account have many friend who have same attribute of user ? how to implement it in DB & how it look like in ER diagram i'm trying to build simple DB project where i have user with (email,password) each user have many friend where the friend also a user...

rails 4 HABTM relation and extra fields on join table

ruby-on-rails,join,entity-relationship,has-and-belongs-to-many
What I have (pseudo code): model Document column :title HABTM :users model User column :name HABTM :documents Document has users (being approvers for document, either approve or not), and in this context join table should have extra column approved for each user. jointable user_id, document_id, approved 1 , 1 ,...