I was simply wondering, how an ISA relationship in an ER diagram would translate into tables in a database. Would there be 3 tables? One for person, one for student, and one for Teacher? Or wo...

In the use of table relationship. What is the difference in the use of solid line and dotted line? For Example TABLE : MESSAGES / TABLE : USERS An User have 0 or Many Messages. Solid line or Do...

I have this error when I build my Web Service: Error 3004: Problem in mapping fragment starting at line 323: No mapping specified for properties JE_TRN_HS.JE_HDR_HSJE_HDR_KEY. Entity i...

What do single line with an arrow mark in ER diagram represent?

I started to study ER diagram when i browse through ER diagram tutorials i found something like figure 1 and i learned Figure 1 And then i tried to create a sample ER Diagram in mysql workbench ...

Using Orcale SQL developer I want to map out a relationship between an employee and manager. However, a manager can only supervise a maximum of 3 employees. Above I have an employee table with M...

I want to generate an ER diagram of an SQL database using Microsoft SQL Server Management Studio (SMSS). However, I don’t know how to. I found this technique online: Making ER Diagram from SQL Serv...

How can edges and nodes be styled using graphviz dot with doubled lines as shown the in the "LEGAL" and "TAX DISC" nodes of the following diagram?

I'm trying to draw an ER diagram describing the following: -"Department" employs "Employees" -Some "Employees" are "Special" and have more attributes -Some of the "Employees" ("Special" and non ...

I am using Entity Framework and I ran into an odd build error. I am building a forum and I set up a table in the database for "ignores" when people don't like each other they will ignore ...

I'm having trouble understanding the difference between partial keys/weak entities and foreign keys. I feel like an idiot for not being able to understand this stuff. As I understand it: Weak Ent...

I've an entity Course and an entity User. There's a many-to-many relationship between course and user, since a course can have many users and a user can be enrolled in many courses. In both entitie...

In order to create an ERD diagram for new projects I have been using Visual Studio's entity framework designer. Essentially I'm creating a "dummy project", adding entity framework via Nuget and dia...

I saw a lot of questions here but no one fits with my problem. I'm trying to create an ER model scalable, and if I want to add more data don't break almost anything, so what I've trying to create i...

Im not quite sure how to read ternary relationships within a ER-Diagram. Lets say this is the ternary relationship that is given. What can I interpret out of that? It says that you have to put y...

I have a JPA (Hibernate) entity: @Entity class Transaction { @ManyToOne private Room room; } When I create a new Transaction, I know the ID of the Room that it should refer to (but don't hav...

can any one say some way to convert SQL code to data diagram like ERD ? for som DBMS like MySQL or general SQL

Imagine you have two entities, Player and Team, where players can be on multiple teams. In my data model, I have a table for each entity, and a join table to maintain the relationships. Hibernate i...

Lets jump to an example that illustrates a table referencing multiple tables : CREATE TABLE Corses ( ID int PRIMARY KEY, ..... ) CREATE TABLE Questions ( ID int PRIMARY KEY, ..... ) CREATE ...

Another Hibernate question... :P Using Hibernate's Annotations framework, I have a User entity. Each User can have a collection of friends: a Collection of other Users. However, I have not been ab...

I have a bidirectional one-to-many relationship with the following entity classes: 0 or 1 client <-> 0 or more product orders When persisting the client entity I want the associated product or...

Is there any way to get an ER model of a database from the server that is connected to my MySQL Workbench?

I have a specific problem with many to many relationship implementations in MongoDB. I have collections of Songs and Artists(Millions document). Here the song can be sung by Many Artists and an ar...

I have a Person Class and Inventory can be two types: Sales and CustomerService. Sales and CustomerService have their unique properties and Peron holds the common properties. I want to be able to...

I have two entities with a foreign key relation: product and category. @Entity(primaryKeys = "id") public class Product { public final long id; @NonNull public final String name; @ForeignKey...