8.2 Databases.dbmss Flashcards
What is a Database Management System (DBMS)?
Systems software for the definition, creation, and manipulation of a database.
What is data management in the context of databases?
The organisation and maintenance of data in a database to provide the required information.
What is a data dictionary?
A set of data that contains metadata (data about other data) for a database.
What is data modelling?
The analysis and definition of the data structures required in a database to produce a data model.
What is a logical schema?
A data model for a specific database that is independent of the DBMS used to build the database.
What are access rights in a database?
Permissions given to users to access, modify, or delete data.
What is a developer interface in a DBMS?
A feature that provides developers with access to relational databases and commands for data definition and modification.
What is Structured Query Language (SQL)?
The standard query language used for interacting with relational databases.
What is the role of a query processor in a DBMS?
It processes and executes queries written in SQL.
How does a DBMS solve the issue of data redundancy in file-based systems?
By storing data in separate linked tables and reducing duplication; foreign keys are used for linking and are stored more than once, with the DBMS flagging potential errors when such data is deleted.
How does a DBMS address data inconsistency?
It stores most items of data only once, ensuring all applications access the same updated data, improving data integrity and ease of maintenance.
How does a DBMS handle data dependency issues?
It separates data from applications, allowing structural changes to be managed by the DBMS with minimal effect on applications, making data structure changes non-disruptive.
What querying features are offered by most DBMSs?
A defined query language such as SQL and often a query-by-example facility to access data independently of its structure.
How does a DBMS manage data more efficiently than a file-based system?
Through structured data entry, storage, modification, and deletion, all managed by the DBMS using a predefined data structure.
What is a data dictionary in a DBMS?
A storage of metadata including table definitions, attributes, relationships, indexing, validation rules, and physical storage details, enhancing data integrity.
What is the purpose of data modelling in a DBMS?
To define and visualise the data structure; for example, through an Entity-Relationship (E-R) diagram or logical schema.
How does a DBMS enhance data security?
By preventing unwanted alteration or access using measures like usernames and passwords, access rights, views, backups, encryption, and audit trails.
What are some common DBMS security measures?
Use of usernames/passwords, access rights, controlled views, regular backups, encryption, and audit trails for tracking user activity.
What is the purpose of the developer interface in a DBMS?
It allows developers to write SQL queries instead of using query-by-example, enabling the creation of more complex database queries.
What is the function of the query processor in a DBMS?
It processes SQL queries using components such as the DDL interpreter, DML compiler, and query evaluation engine to execute and optimise queries.
What does the DDL interpreter in the query processor do?
It interprets Data Definition Language (DDL) statements and records them in the data dictionary.
What role does the DML compiler play in the query processor?
It compiles Data Manipulation Language (DML) statements into low-level instructions and optimises them for execution.
What is the function of the query evaluation engine?
It executes the compiled low-level instructions resulting from SQL queries.
