Flashcards in 1.3.2 Databases Deck (17)
What type of database stores information in a single large table
What type of database stores data in many smaller tables, linked together using keys?
What are unique attributes that can be used to identify a record in a table?
What are the primary keys from another table and are used to link tables together?
What type of model can be used to visually describe the relationships between the different entities in a database.
Entity relationship model
What is the process of converting a flat file database into a relational one.
What is a data structure used to shorten the length of time it takes to search a database.
What is Optical mark recognition (OMR) used for and hoe doe it work?
OMR is often used to capture data that is to be held in databases. A light is then shone at the paper and, as the mark made by the user reflects less light than the empty boxes, the software can work out which answer was selected.
Which rule must be obeyed for a table to be in 1st Normal Form?
Each field must only contain one piece of data and all attributes in the table must depend on the primary key
Which rule must be obeyed for a table to be in 2nd Normal Form?
It must be in 1st Normal Form and no entities can be partially dependent on the primary key.
(The Whole Key)
Which rule must be obeyed for a table to be in 3rd Normal Form?
It must be in 2nd Normal Form and have no transitive dependencies. The entities must be dependent on no other entities than the primary key.
(Nothing But The Key)
What is referential integrity?
Every foreign key must refer to the primary key of an existing record.
What is an orphan record?
A record with a foreign key where the record, with the linked primary key, has been deleted.
In transaction processing what is atomicity?
Either every part of the transaction must be successful or the whole transaction must fail.
In transaction processing what is consistency?
All data entered in the transaction must follow the rules of the database.
In transaction processing what is Isolation?
When multiple sessions are operating at the same time on the same database, they do not effect the outcome of the processing of the other session. The data will be as if one session carried out its transaction followed by the other.