erd | DEPRECATED : Project moved to http : //drupal.org/project/erd

Here is how my ERD looks like

I have users, that have autoincremented ID. When new user is added, there is trigger which inserts into biodata (in biodata table will be later info about user DOB, city etc.) new record. Biodata user_id is also autoincremented and I am using following trigger to fill it whenever new user is added:

I know that there are already some solutions here but unfortunately they did not help me with my problem. I want to move a satellite image around a planet image in a circular path. I know how to move it in a line from left to right but I don't get it how to make the circle. This is my code so far

I am creating a database which keeps track of customers, items, transactions, and more. I am having trouble describing the relationship between Customers and Items which is represented by buys. The relationship, buys, represents a Customer purchasing Items at a register. The transaction, buys, may include one item, multiple items, and/or the same item multiple times in a single transaction; additionally, multiple Customers may purchase the same item on separate occasions.

What attributes does the relationship buys need in order to keep track of all the items purchased?

Currently, I am proposing an attribute buys.id; however, it seems a composite key is necessary. The keys could (buys.id, Customer.id, Items.id), yet if a customer were to add the same item twice, then these rules would break. I would also include a date attribute. Additionally, a quantity attribute could be added to relationship.

The relationship could be described like so:

It does appear that this would be able to satisfy all the rules laid forth, but it seems a bit cumbersome.

Is there a way to improve this design?

(I need a refresher on this stuff if anybody knows a good book or video)

EDIT:

This answer from another post could answer this question.

I'm using MariaDB and python.

I have all the tables I needed to create for my back-end application, but when I try to add in foreign keys for relationships it throws error when the migration is called. the database is postgreSQL Goal: I would like to make 1 more table that references all the foreign keys linking all the tables to the 1 table. like the example blow.

----UPDATE

I have cloned the repo in an other directory and went throw the all process again, this time though I noticed that the issue comes out only after using:

i am trying to create an ERD diagram for a crowdfunding service. I am not sure if i took Entities right and relationships between them.

The task is create Rules(Sentences for relationship) and Find needed Entities.

Project owners call for public participation in order to finance their innovative ideas, namely a product. The public pre-orders a product, which is offered at an initial price.

What are the entites and relationships ?

This is the databases ERD my final project for school is on (at the bottom), I am required to make a database using this information. I understand how to add the tables that are setup like 'trainer' and even how to add self-joining tables to my database, but something we have NOT learned is what it means or what to do when there is no Id at the end? Like 'evolvesfrom' and 'pokemonfightexppoint'.

Do you not have to add an Id at the end? From what my teacher taught us, I assumed you did. From what I see in this ERD is how evolvesfrom is self-joining itself to pokemonId. I know how to complete this only when there is an Id at the end of evolvesfrom.

For something like trainerId, it is super easy to understand how to add the constraints and everything like so:

I am currently creating a database for my school project based on this information:

If you look at the ERD of the pokemon database I posted, on the pokemonFight table, it includes pokemonFightExpPoint. Now after talking to someone in my class, we figured out there's no constraint needed (other than the check constraint). But also, the pokemonId , battleId, and battleLocationId are foreign keys from the other tables.

It was noted in my assignment that

Pokémon can play any battles at any battle locations. In other words, the battle experience points are functionally dependent on Pokémon, battle, and battle location.

I am just wondering if in order to add the PokemonFightExpoint column, you NEED to add pokemonId, battleId, and battlelocationIds to this table? Is it somehow getting data from these foreign keys that were added?

Thanks in advance.

Question: Create a single trigger named trg_job_date that will update the JOB_LAST_UPDATE column in the job table to the current date on insert or update. Test the trigger with an insert and update statement – include the insert and update statements.

So I'm trying to update job_last_update in job through a trigger but I read that I can have the same table I want to update in the trigger. My main problem is that job_last_update is only available in the job table.

Here is the erd:

And here is my code so far: