A.1 Basic Concepts Flashcards
Data
Data can be any one of several different type
(eg. text, Boolean, etc.) but has no intrinsic meaning to a human
Information
Data becomes information when it is put into context that gives meaning to human
Information = Data + context
Information system
–> Any organized system for the collection, organization, and communication of information
–> Grouped into components that interact to produce information
–> include one or more databases as part of their overall structure
What is an Information System made up of ?
Hardware
Software
Data
People
Network
Process
Database
–> An organized collection of structured information, or data, typically stored electronically in a computer system.
–> Refers to a complete system
Needs for databases
- Size of Data –> stores and manages a large amount of data on a daily basis
- Accurate –> as it has all sorts of build in constraints, checks etc. The information available in a database is guaranteed to be correct in most cases.
- Easy to update –> using various Data Manipulation languages (DML) available (eg. SQL)
- Security of data –> are user logins required before accessing a database and various access specifiers. These allow only authorised users to access the database.
- Data Integrity –> ensured by using various constraints for data. Makes sure that the data is accurate and consistent in a database.
- Easy to access and research data –> done using Data Query Languages (DQL) which allows searching of any data in the database and performing computations on it
Transactions
–> Refers to a set of related database operations that are executed as a single unit of work
–> Which must either all be completed successfully or none of them are completed at all.
–> Transactions are used to ensure data consistency and integrity within a database.
Consistency
–> Consistency in databases means that data must meet certain rules and constraints defined by the database.
–> If a transaction tries to insert or modify data that violates these rules, the entire transaction is undone, and the user is notified of the error.
–> The database must remain in a valid state at all times.
Data Integrity
Overall completeness, accuracy and consistency of data
Ensures data is complete, unchanged, and error-free and is maintained through standard procedures and error-checking and validation procedures during updates
Database transaction
A logical unit that is independently executed for data retrieval or updates
These transactions must be ACID
ACID
Atomicity –> ensures all operations within the work unit are completed successfully or else the transaction is aborted
Consistency –> ensures the database properly changes after a successful committed transaction
Isolation–> Enables transactions to operate independently of and transparent to each other
Durability –> Ensures that the results or effect of a committed transaction persists in case of a system failure
Explain concurrency in a data sharing situation.
Refers to the ability of multiple users or applications to access and modify the same data simultaneously, without causing conflicts or inconsistencies
Describe the two functions databases require to be performed on them.
- Query functions –> A query is a request for data and information from a database table or series of tables. This data may be generated as results returned by Structured Query Language (SQL) or as pictorials, graphs or complex results
- ADD, DELETE, and UPDATE are all functions that can be performed on a databse
Data Validation
Checking if the input data to ensure it conforms with the data requirements of the system to avoid data errors
Data Verification
A method of ensuring the user types in what he or she intends. Make sure the user isn’t making mistake
