Hello

that depends on your specific database system. There are Database systems where you can
type in: select myBirthday - now() as "My age is:" ;

You need to know the current-date function...

I did not change your table tbl_Author which already has Author-Name. Therefore I left out your 3rd table !

Hello,

in tbl_poems exists a transitive dependency poem-ID -> Author-ID -> Book-ID. Therefore, this table does not satisfy 3NF. fk Author-ID should be removed and inserted into tbl_Book. The...

Ah, you again

Did you proceed in understanding EERM?

I call people who put a magical, universal "id" column with an auto-increment on all their tables "id-iots" ! (Joe Celko)

Hi chsarp_vijay,

Derby is pure Java. if you want to use it, you must program Java. Why not using SQL Anywhere/Ultralight from worldwide leader in mobile computing, Sybase? There mobile computing...

Hi motofoto

There is kind of inheritance - in EERM - where we have Generalization / Specialization, such called isa-relationships. Maybe you should first design an EERM. Your implementation idea...

I have to make an extension:
Sometimes there are more than one superkey of a relation. In such case also all redundant attributes have to be removed and the remaining subsets of attributes are then...

hi mertucci,

are in doing data modelling?
Superkey is any subset of attributes that uniquely identifies the tuples of a relation. This subset need not be minimal, that is, one can remove some...

Hi friend,

I am viewing your data dictionary and erm. Well, something seems to be wrong: some trouble with keys, composite keys, also the graphic of the erm emerges in a disordered manner. The...

hi

i ve just checked your erd und dd:

1. items must have primary key, e.g. foreign key order_id + item_nb (1,2,3..)
item_nb is necessary, if a certain order contains more then 1 item.

2....

hi,
if you design an entity relationship model (ERM) there are only entities and relationships. There aren't any "tables" there. Once you might map your ERM into relational model, which consists of...