A key process in database development is obviously database modelling and the main diagrams used are ERD. A number of notations exist, some particular to evangelised by particular DBMS. Here I am documenting a short course/notes about ERD modelling using the Barker’s notation, which is greatly adopted by Oracle.
As usual here is the link, do feel free to comment!
Short notes on Barker’s ERD Notation
Being blessed by being Maltese, it was inevitable that a love for the sea would grow. Every Summer I would head off for the sea snorkeling. Then at the age of twenty I started the diving course and four years ago I started taking some underwater photography. My all time favorite was at the very beginning of a dive! We start descending, then for some reason I turn back to check on my buddy, Roberto! Click! A great shot is taken! Judge for yourself and comment!
- Roberto’s Underwater Profile
Some of my favourite shots of the Upper Barrakka at Valletta, Malta as seen from St. Angelo, Birgu.
I was once asked by a fellow colleague if it was possible to have an SQL statement that would not allow employees from being registered to events that occur simultaneously.
Consider a database that stores a list of persons and a list of events. Employees would eventually be registered as event attendees. It is possible that multiple events occur at the same time and therefore it is required that the SQL statement prevent any persons from being registered as attendees of conflicting events. It was required that the solution be all in one SQL statement for some reason whatsoever.
The SQL solution is found attached together with a supporting report! As always all feedback and queries are welcome!
Register employees for non conflicting events
One of my favourite diving sites is the Um El Faroud at Wied iz-Zurrieq and one of my very first shots with the new camera and underwater housing was as I surfaced from a dive. It was more luck than skill back then but yet a great addition to my collection.
I had just got hold of my new Canon Powershot A710 IS and headed down to the newly refurbished Valletta Waterfront around July 2007 and this was one of my very first shots! The waterfront was not yet bloated with restaurants and the real beauty of this site can be appreciated!