Tag Info

New answers tagged

0

The answer from MDCCL is a superb summary of the concepts behind superclass/subclass or generalization/specialization as depicted at the EERD level. This answer is intended to point out three design patterns or techniques that are worth knowing when the time comes to turn the EERD into a relational design, based on defined tables with defined columns. ...


0

The Answer by MDCCL is fascinating, educational, and presumably correct (though above my pay-grade). In contrast, I re-interpreted the Question and went back to basics for the simplest possible solution. Perhaps I am cheating and not truly answering the Question… but here goes anyways. I was confused when reading and re-reading the Question. When seeing ...


0

There is no earth-shattering difference between a data model depicted in UML notation versus a data model depicted in any of the many common ER notations. They all depict the most important elements: entity types and relationships. Depending on which graphical convention you choose, there may be other features of the model which are conveyed, such as the ...


0

I think you answered your own question. E-R diagrams are meant to be problem solving diagrams for the sake of creating a database schema, whereas UML are supposed to model a completed db. I personally don't place a huge amount of value on ER diagrams, as I would personally do such brainstorming in my head, but I imagine many people would swear by them. As ...


4

It is great that you are taking the time to understand, classify and model the data you are dealing with since, from my personal experiencie, all this makes the whole development process easier and very flexible for future changes. And I am quite sure that you are also aware of this already. Preliminary data model and assumed business rules I defined a ...


4

I think you are trying to blend together concepts from object modeling and concepts from data modeling in a way that isn't helping you to clarify your own understanding of the problem. I hope I can clear the clutter a little without too much rambling. The relational model, as such, does not support inheritance, never mind polymorphism. This means that a ...


3

All the information you need is in the catalog, have a look at the tables: information_schema.table_constraints information_schema.key_column_usage information_schema.constraint_column_usage However, if you want something more visual have a look at: http://schemaspy.sourceforge.net/ It will reverse engineer your schema and produce html output


1

You could try this or this for generating Entity Relationship Diagrams.


1

Well the database design is ok. But I would suggest one change. Instead of making a direct join between Teamroster and Player, I would suggest this design: Table Player: id (PK) PlayerName ... Table Teams: id (PK) TeamName ... Table: PlayerTeamPositions team_id (PK) (FK references table teams) player_id (PK) (FK references table players) position_id ...


2

IMHO This is not good design. You have teamname in league table and teams table. What also is not good to have mixed conventions (plural and singular for table names) I would note that you should also put unique index on this fields: toplane, jungler, midlane, adc, support. create unique index teamroster_unique_idx on (toplane, jungler, midlane, adc, ...


0

Once, when I was truly desperate for an ER diagram of an Oracle database, I used MS Access, and the relationship diagram tool inside it. I created table links from an Access DB to the Oracle tables, and defined the references inside Access. I then cranked up the relationship diagram, and moved the boxes around until it was at least presentable. This won't ...



Top 50 recent answers are included