CS Key Terms:
Database: Structured collection of items of data that
can be accessed by different application programs.
Table: Group of similar data, in a database, with
rows for each instance of an entity and columns for each attribute.
Relational Database: Database where the data items
are linked by internal pointers.
Record (Database): Row in a table in a database.
Field: Column in a table in a database.
Tuple: One instance of an entity represented by a row in a table.
Entity: Anything that can have data stored about it,
for example, a person, place, or event.
Attribute (Database): Individual data item stored for
an entity, for example, for a person, attributes could include name, address, and date of birth.
Candidate Key: Attribute or smallest set of
attributes in a table, where no tuple has the same.
Secondary Key: Candidate key that is an alternative to the primary key.
Primary Key: Unique identifier for a table. It is a
special case of a candidate key.
Foreign Key: A set of attributes in one table that
refer to the primary key in another.
Relationship: A situation in which 1 table in the database
has a foreign key that refers to the primary key in another table in the database.
Referential Integrity: Property of database that
doesn’t contain any values of the foreign key that aren’t matched to the corresponding
primary key.
Index: Data structure built from 1 or more columns in the database table to speed up searching for data.
Entity Relationship Model (E-R): Graphical representation
of database and relationship between entities.
Composite Key: A set of attributes that form a primary
key to provide a unique identifier for a table.
Normalization: Process of organising data stored into
2 or more tables and relationships between tables, so data redundancy is
minimised. First Normal Form (1NF): Status of a relational database, in
which entities don’t contain repeated groups of attributes. Second Normal Form
(2NF): Status of a relational database, in which entities in 1NF and any
non-key qualities depend upon the primary key. Third Normal Form (3NF):
Status of a relational database in which entities are in 2NF and all non-key
attributes are independent.
Database Management System (DMS): System software for the definition, creation, and manipulation of databases. Data Management:
Organization and maintenance of data in the database to provide required
information.
Data Dictionary: Set of data that contains metadata
(data about other data) for a database.
Data Modelling: Analysis and definition of the data
structures required in the database and to produce a data model.
Logical Schema: Data model for a specific database that
is independent of DBMS used to build that database.
Access Rights: Permissions given to database users to
access, modify/delete data.
Developer Interface: A feature of DBMS, that provides
developers with commands required for the definition, creation and manipulation of a database.
Structured Query Language (SQL): Standard query
language used with relational databases for data definition and data modification.
Query Processor: Feature of DBMS, that processes and
executes queries written in SQL.
Data Definition Language (DDL): Language used to
create, modify and remove data structures that form a database.
Data Manipulation Language (DML): Language used to
add, modify, delete and retrieve the data stored in a relational database.
SQL Script: List of SQL commands that perform given
tasks often stored in a file for reuse.
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