1.3.2 Databases Flashcards
Define a flat file database?
A database that consists of a single file
Define a primary key?
A unique identifier for each record in a table
Define a secondary key?
An index other than the primary key used to search and sort through the database with more convenience and speed
Define a foreign key?
The attribute which links two table together
A husband and a wife are an example of what type of relationship?
One-to-one
Multiple children to a mother is an example of what type of relationship?
One-to-many
A student to a A-level subject is an example of what type of relationship?
Many-to-many
What 3 things must happen for a database to be in 1st normal form?
All field names must be unique
No two records can be identical
Each table needs a primary key
What 2 things must happen for a database to be in 2nd normal form?
The database is in 1st normal form
There are no partial dependencies (composite keys)
What 2 things must happen for a database to be in 3rd normal form?
The database is in second normal form
There are no non key dependencies
What is referential integrity?
Referential integrity is the process of ensuring consistency as it makes sure that information is not removed if it is required elsewhere in a linked database
What does ACID stand for?
Atomicity, Consistency, Isolation, Durability
What does atomicity mean?
A transaction must be processed in its entirety or not at all
What does consistency mean?
A transaction must maintain referential integrity rules between linked tables
What does isolation mean?
Simultaneous execution of transaction should lead to the same result as if they were executed one after the other
