I understand PK means primary key and FK means foreign key, but
exactly what do "rK" (in section 3) and "PF" (in sections 3, 4, 6, 7, and 8) mean in this article? http://www.databaseanswers.org/tutorial4_data_modelling/index.htm
And exactly what does "FF" mean (within the Customer_Addresses table) in this article? -I am new therefore it would only allow me to place in one hyperlink, so copy/paste this to visit the page I am asking about:
Edit: also, I realize the concepts of primary secrets and foreign secrets, but what exactly are other ones employed for?
It is the dude's own little annotation system for his diagrams. It isn't like you should utilize them. He defines them here:
The strange-searching ones, "rK" and "FF", are simply rendering issues: they are said to be FK and PF correspondingly.
The website is greater than a little sporadic from the design perspective... he's clearly not using data modeling abilities in the making of the website.
PF most likely means the column is both a principal key along with a foreign key (i.e., in times of fourth normal form, i.e., subtype/supertype modeling)
rk = it appears such as the letter F (upper situation) could not squeeze into the circle. The circle seems to become more compact than these. :)