Database Management Systems (DBMS) (Cambridge (CIE) A Level Computer Science): Flashcards
Exam code: 9618
1/220Still learning
Know0
- FrontDBMS Features
Define DBMS.
Was this flashcard helpful?
Cards in this collection (22)
Define DBMS.
A DBMS (Database Management System) is software used to create, manage and interact with databases.
Define logical schema.
A logical schema is the overall logical design of the database, covering tables, fields, relationships and constraints, showing how data is organised independently of how it is physically stored.
How does a DBMS maintain data integrity?
It enforces rules and constraints, so data changed in one place is updated everywhere, and each foreign key has a corresponding primary key.
A DBMS uses such as primary keys and foreign keys to enforce data integrity.
A DBMS uses constraints such as primary keys and foreign keys to enforce data integrity.
Define concurrency control.
Concurrency control allows multiple users to access the database at the same time without errors.
Define data independence.
Data independence ensures that changes to storage methods do not affect how the data is used.
How does a DBMS solve data redundancy?
A DBMS centralises data, so it is stored once and referenced whenever it is needed.
How does a DBMS solve data inconsistency?
A DBMS ensures data consistency by updating a single source of truth.
Define data dictionary.
A data dictionary defines all the data elements across the system, such as field names, table names and data types.
What tools does a DBMS provide for data modelling?
A DBMS uses data modelling tools, such as E-R diagrams, to define entities and their relationships.
How does a DBMS improve data security compared with a file-based system?
A DBMS supports user accounts, access rights and permissions for individuals and groups, whereas a file-based system has poor control over who can access or change data.
How does a DBMS reduce the risk of data loss?
A DBMS includes automated backup and recovery tools.
True or False?
In a file-based system, backup procedures are usually automated.
False.
In a file-based system backups are often manual and inconsistent. It is a DBMS that provides automated backup and recovery tools.
What does the developer interface allow developers to do?
It allows developers to write database queries using Structured Query Language (SQL).
Why is SQL more flexible than query-by-example?
SQL allows developers to create more complex and precise queries to search, update or manage data, whereas query-by-example tools are visual and simplified.
What is the query processor responsible for?
The query processor is responsible for handling and executing SQL queries.
Name the three components of the query processor.
The DDL interpreter, the DML compiler and the query evaluation engine.
What does the DDL interpreter do?
It interprets Data Definition Language commands such as
CREATE,ALTERandDROP, and updates the data dictionary.What does the DML compiler do?
It compiles Data Manipulation Language statements such as
SELECT,INSERTandUPDATEinto low-level instructions, and optimises the query.What does the query evaluation engine do?
It executes the compiled instructions to retrieve or manipulate the actual data in the database.
True or False?
The DML compiler updates the data dictionary.
False.
The DDL interpreter updates the data dictionary. The DML compiler compiles and optimises DML statements.
Together, the query processor's components ensure that a query is interpreted, optimised and executed .
Together, the query processor's components ensure that a query is interpreted, optimised and executed efficiently.
Sign up to unlock flashcards
or