Database Management Systems (23CSE202) - Practice Flashcards

Comprehensive vocabulary flashcards for Database Management Systems Unit 1, covering introductory concepts, SQL languages, relational models, keys, and E-R modeling.

Database Management System (DBMS)

Software that enables users to define, create, maintain, and control access to databases efficiently; it is a collection of interrelated data and a set of programs for accessing and managing that data.

Data

Raw facts and figures that have not been processed, such as the value "101" or the name "Ravi".

Information

Processed data that has meaning, such as the statement "Student 101 is Ravi from the CSE department."

Metadata

Information about the database structure itself, also known as "data about data," which includes tables, fields, data types, and relationships.

Data Abstraction

A technique that simplifies interaction with the database by hiding storage details and showing users only the required information through three levels: Physical, Logical, and View.

Physical Data Independence

The ability to change physical storage structures (e.g., changing from a sequential file to an indexed file) without affecting the logical schema or application programs.

Logical Data Independence

The ability to change the logical schema (e.g., adding a new attribute like "DateOfBirth") without affecting the user views or application programs.

Data Redundancy

A problem in traditional file processing systems where the same data is stored multiple times, leading to wasted storage and potential inconsistencies.

Data Consistency

A state where all users see the same accurate information, ensured by a single copy of data in a DBMS.

Data Definition Language (DDL)

A category of database languages used to define database structures (schemas), including commands such as CREATE, ALTER, DROP, and TRUNCATE.

Data Manipulation Language (DML)

A category of database languages used to manipulate data, including commands such as INSERT, UPDATE, DELETE, and MERGE.

Data Query Language (DQL)

A category of database languages used specifically for retrieving data, represented by the SELECT command.

Data Control Language (DCL)

A category of database languages used for security control, including GRANT (to provide permissions) and REVOKE (to remove permissions).

Transaction Control Language (TCL)

A category of database languages used to manage transactions, including COMMIT (to save changes), ROLLBACK (to undo changes), and SAVEPOINT.

TRUNCATE

A DDL command used to delete all records from a table while keeping the table structure intact.

DROP

A DDL command used to completely remove a table and its structure from the database.

MERGE (UPSERT)

An operation used to insert, update, or delete records in a target table based on matching conditions from a source table.

Relation

The relational database term for a table that contains data organized into rows and columns.

Tuple

The relational database term for a single row in a table.

Attribute

The relational database term for a column in a table representing a property of an entity.

Domain

The set of all possible and valid values that an attribute can take, such as integer values from $0$ to $120$ for an "Age" attribute.

Degree

The number of columns (attributes) present in a table.

Cardinality

The number of rows (tuples) present in a table.

Super Key

A set of one or more attributes that can uniquely identify a tuple within a relation.

Candidate Key

A minimal super key that contains only the necessary attributes required to uniquely identify a record.

Primary Key

A candidate key selected to uniquely identify records; it must be unique and cannot be NULL.

Foreign Key

An attribute in one table that refers to the primary key of another table to establish a relationship between them.

Composite Key

A primary or candidate key that consists of more than one attribute (e.g., combining "RollNo" and "CourseID").

Database Schema

The structural blueprint of a database that specifies table names, attributes, data types, and constraints; it rarely changes.

Database Instance

The actual data stored in the database at a specific moment in time, which changes frequently as records are managed.

Entity Integrity Constraint

A rule stating that a primary key cannot contain a NULL value.

Referential Integrity Constraint

A rule stating that foreign key values in a table must exist in the primary key column of the referenced table.

Entity-Relationship (E-R) Model

A high-level conceptual data model used for database design, developed by Peter Chen in 1976, that describes entities, attributes, and relationships.

Weak Entity Set

An entity that cannot be uniquely identified by its own attributes and depends on an identifying relationship with another entity; represented by a double rectangle in E-R diagrams.

Specialization

A top-down design process where a higher-level entity set (superclass) is divided into lower-level entity sets (subclasses) based on distinguishing characteristics.

Generalization

A bottom-up design process where multiple lower-level entity sets with common attributes are combined into a higher-level entity set.

Inheritance

A property of the Extended E-R model where subclasses automatically acquire the attributes and relationships of their superclass.

Aggregation

A feature that treats a relationship set as an entity so that it can participate in further relationships with other entities.

Total Participation

A constraint where every entity in a set must participate in a relationship at least once; represented by a double line in E-R diagrams.

Crow's Foot Notation

A popular industry notation for E-R diagrams where cardinality is shown using symbols (I for one, O for zero, and < for many) and attributes are listed inside the entity rectangle.

Query Optimizer

A component of the query processor that evaluates multiple possible execution plans for a SQL query and chooses the most efficient one.

Buffer Manager

A component of the storage manager responsible for managing data in main memory and transfering data between the memory buffer and physical disk storage.