0
votes
0answers
341 views

Multi user messaging database design

I'm designing a database for a new project and I'm looking for some feedback on the design before I start to implement. It basically consists of secure messaging system with those abilities : One ...
4
votes
1answer
106 views

Probable circular dependency, but query still runs

I built this ER diagram in MySQL Workbench and it will run and generate the database. My concern is that the relationship between the employees, departments, positions, and employment_statuses is a ...
0
votes
1answer
250 views

Database for opening times of locations

I'm designing a database for opening times and created this solution. The specifications of the database which will be a MySQL are, that a location have standard opening times in a week and can ...
3
votes
1answer
454 views

What relationship type to use for this messaging system?

I am trying to make a small messaging system. It should have these properties: One user can send a message to one or many users Messages can be sent only to registered users (i.e. to an existing ...
4
votes
2answers
792 views

Is my EER Diagram correct? Why use relationships?

This is the first time I've made an Entity Relationship Diagram (ERD) for MySQL. Prior to this, I would never create relationships between tables, I would simply create the tables in MySQLAdmin and ...
1
vote
1answer
215 views

Referring to super parent or as a separate entity?

I have this person table as super parent, id firstname lastname email telephone ... ... and user table as a child id person_id (FK) password username screenname ... ... They must be 1:1 ...
0
votes
1answer
2k views

SQL keyword difference between MySQL and Oracle 10g?

Good afternoon, Are there differences between Oracle 10g and MySQL with the CREATE, ALTER, DROP, REF, PRIMARY KEY, FOREGIN KEY and attribute variable type keywords? The reason I ask, is I'm planning ...