1.3.2 databases Flashcards
what is a relational database?
a database which recognises the difference between entities and uses different tables for each entity
what is an entity?
an item of interest about which information is stored
what is a flat file?
a database that consists of a single file usually about one entity
what is a primary key?
a unique identifier for each record in a table
what is a foreign key?
the attribute which links two tables together
what is a secondary key?
an Index other than the primary key used to search and sort though the database with more convenience and speed
what is normalisation?
this is the process of coming up with the best layout for a relational database
what does normalisation try to accomplish?
no redundancy, consistent data throughout linked tables, records can be added and removed without issues, complex queries can be carried out
what is an index?
an index is a data structure used to look up and access data in database quickly
is the primary key automatically indexed?
yes
what does capturing data mean?
capturing data is the process of getting the information you wish to use
what method do banks use to capture data from cheques?
they use magnetic ink character recognition to get all the details from the amount which must be entered manually
what does selecting data mean?
selecting data is the process of reducing excess information to obtain only the data you require
what does managing the data mean?
managing the data means to manipulate the information in any type of way such as through sorting through it or selecting certain parts using SQL
what is the most common language used to manipulate data in databases
SQL
what are the requirements to be in first normal form?
to be in first normal from there must be no attribute that contain more than a single value in a cell
what are the requirements to be in second normal form?
the database is in first normal form, there are no composite keys
what are the requirements to be in third normal form?
the database is in second normal form, there are no non key dependencies
what does SQL stand for?
structured query language
what is SQL?
a declarative language used to manipulate databases
what is referential integrity?
referential integrity is the process of ensuring constancy as it makes sure that information is not removed if it is required elsewhere in a linked database
what is a transition defined as?
a transaction is a single operating executed on data
what does ACID stand for?
Atomicity, consistency , isolation and durability
what does atomicity in ACID mean?
a transition must be processed in its entirety or not at all
