erd

问题 In Visio I can only alter one side of the relationship. If I want a "1-M" relationship, I have to choose "Identifying", but this automatically makes the FK becomes PK, which doesn't seem right to me. Someone with the same problem said it was a flaw, so there is no way around it in visio? 回答1: Make sure "Required" is checked for the foreign key column(s) in the column list in the child table. If you do that you should see the relationship depicted as: -II--O<-, which I guess is what you want.

问题 In Visio I can only alter one side of the relationship. If I want a "1-M" relationship, I have to choose "Identifying", but this automatically makes the FK becomes PK, which doesn't seem right to me. Someone with the same problem said it was a flaw, so there is no way around it in visio? 回答1: Make sure "Required" is checked for the foreign key column(s) in the column list in the child table. If you do that you should see the relationship depicted as: -II--O<-, which I guess is what you want.

问题 I'm writing a java code using ormlite. I was wondering if it's possible to generate an ERD from the JPA annotations in my code. Basically, I need the reverse of this: How can I transform Entity-Based diagram to a JPA java code 回答1: IntelliJ IDEA (Ultimate) provides JPA to ER-Diagram generator. In the Persistence tool window, select appropriate node. Then use context menu to select "ER Diagram". Note that JPA facet must be linked to module and UML plugin should be active. 来源： https:/

问题 I realise that the answer to these types of questions are often "it depends" but still I wondering what the general consensus might be. I am dealing with multiple entities such as Company Charity Auditor Stocktaker etc etc... Which all have contact information such as e-mail, telephone and address. The two design methods I was thinking to store the contact info were Method 1) create role tables between the contact tables and company, charity, auditor and stocktaker. dbo.Company -> dbo

问题 I realise that the answer to these types of questions are often "it depends" but still I wondering what the general consensus might be. I am dealing with multiple entities such as Company Charity Auditor Stocktaker etc etc... Which all have contact information such as e-mail, telephone and address. The two design methods I was thinking to store the contact info were Method 1) create role tables between the contact tables and company, charity, auditor and stocktaker. dbo.Company -> dbo

问题 What is the difference between ERD (Entity relationship diagram) and EERD (enhanced entity relationship diagram)? 回答1: Entity-Relationship model You have relationships (image source) and attributes (image source) that can also be primary keys (image source) Enhanced entity–relationship model You have the same as with the ER model plus specialisation partitioning (which are multiple specialisations) generalisation aggregation keys are annotated differently: 回答2: I would add that ER model is

问题 I have a PostgreSQL database. I want to get its ERD. How can I do so? 回答1: We used DBVisualizer for that. Description: The references graph is a great feature as it automatically renders all primary/foreign key mappings (also called referential integrity constraints) in a graph style. The table nodes and relations are layed out automatically, with a number of layout modes available. The resulting graph is unique as it displays all information in an optimal and readable layout. from its site

问题 I am confused about "entity set" and "relationship set". I am aware of "entity" and "relationship". Is there any clear example for entity set and relationship set which shows the real use cases of these terms? ___________ /\ ___________ | | / \ | | | Teacher |-------- /Tea \--------| Student | |___________| \che / |___________| \s / \/ In the above diagram Teacher and Student are entities and Teaches is a relationship. 回答1: Originally in Entity-Relationship Modeling: An entity is an

问题 How to hide key information from table depiction in ERD in Sparx Enterprise Architect? 回答1: Open the context menu of the element Features.../...Visibility in the Hide Stereotypes box enter PK,FK That should hide them. 来源： https://stackoverflow.com/questions/42341146/how-to-hide-key-information-from-table-in-erd-in-sparx-ea

问题 I'm currently designing a database design for a thesis repository. I came across this situation: • A student can submit ONLY ONE thesis, and a thesis can be submitted by MANY students. However, I do not want to make the Thesis ID repeat for the Thesis table. Should I use a junction table? I have made an initial design (below) with one. Am I in the right track? 回答1: You are almost there. Only I have a comment on the Thesis_Students table, I see you have both ThesisID and StudentID as PK, which