security, privacy and data integrity Flashcards
file based-approach
the data is stored in one or more separate computer files
relational database
a way of structuring info in table rows and columns
file-based limitations
- data redundancy (repeated data)
- data dependency (changes to data mean changes to the program accessing the data)
- lack of data integrity
- lack of data privacy
relational database pros
- multiple tables are linked together: which reduces data redundancy, increases data integrity
- program-data independence: structure of data can change and does not affect the program and vice-versa
- complex queries can be easily written: to find specific data
- different users can be given different access rights: improves security
entity
the concept or object in the system that we want to model and store info about
attributes
a column or field in a table
primary key
unique identifier for each tuple
foreign key
a field in one table that links to a primary key in another table
candidate keys
a set of keys that can be used to uniquely identify a record
tuple/record
data in one row of a table
referential integrity
- making sure that tables do not try to reference data that does not exist
- a primary key can’t be deleted unless all dependent records are already deleted
- a primary key can’t be updates unless all dependent records are already updated
- every foreign key value has a matching value in the corresponding primary key
how can relational database reduce data redundancy
- because each record of data is stored once and referenced by a primary key
- as data is stored in individual tables
- tables are linked by relationships
- by this proper use of primary and foreign eys
- by enforcing referential integrity
developer interface
- creates user friendly features
- creates outputs
- creates interactive features
query processor
- creates SQL queries
- searches for data that meets set criteria
- performs calculation of extracted data
data dictionary
stores all the info about the database e.g: fields, datatypes, keys
tasks performed by DBMS developer interface
- create a table
- set up relationships between tables
- create a form
- create a report
- create a query
DBMS software to ensure the security of data
- issue usernames and passwords
- access rights
- regular backups
- encryption of data
normalization
a method to remove or reduce data redundancy
1NF
- no repeated group of attributes
- no duplicate rows
- all attributes should be atomic
2NF
should be in 1NF + no partial dependencies
3NF
- should be in 1NF and 2NF + have no non-key dependencies
external schema
the individual’s view of the database
logical schema
describes how the relationships will be implemented in the logic structure of the database
conceptual schema
describes the views which user of the database might have