The database approach to holding data allows data to be stored centrally once, with access being given where needed.
This central approach unlike the file one, also means that if a single piece of information needs updating ie a person's address it need only be done the once. Which in itself reduces not only the time for the update, but also possible errors between the databases.
With the database approach back-up and recovery is also undertaken centrally.
Relational databases are sets of tables which have a unique identifier called a 'primary key' for each entry.
The biblio library database can be accessed using Structured Query Language (SQL).
The display below shows an sql accessing just the 'titles' table so as to print out the ISBN number and title of a specific book.
The relational tables contain the total information held on a book split into smaller, quicker accessed bite sized pieces.
The following page, also on my web space, contains 10 additional SQL queries of multiple tables within the biblio book database.
http://www.student.city.ac.uk/~abhj012/lesson_7_all_sql.mht
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