AIS Chapter 4

database

A set of interrelated, centrally controlled data files stored with as little data redundancy as possible. A database consolidates records previously stored in separate files into a common pool and serves a variety of users and data processing applications.

database management system

The program that manages and controls the data and the interfaces between the data and the application programs that use the data stored in the database

database system

The database, the DBMS, and the application programs that access the database through the DBMS.

database administrator

The person responsible for coordinating, controlling, and managing the database.

online transaction processing database

Database containing detailed current transaction data, usually in third normal form. Focuses on throughput, speed, availability, concurrency, and recoverability. Often used concurrently by hundreds of users.

data warehouse

Very large databases containing detailed and summarized data for a number of years used for analysis rather than transaction processing.

business intelligence

Analyzing large amounts of data for strategic decision making. There are two main business intelligence techniques: online analytical processing (OLAP) and data mining.

online analytical processing

Using queries to investigate hypothesized relationships among data; one of two main techniques used in business intelligence.

data mining

Using sophisticated statistical analysis to “discover” unhypothesized relationships in the data.

record layout

Document that shows the items stored in a file, including the order and length of the data fields and the type of data stored.

logical view

How people conceptually organize, view, and understand the relationships among data items. Contrast with physical view.

physical view

The way data are physically arranged and stored in the computer system. Contrast with logical view.

schema

(1) A description of the data elements in a database, the relationships among them, and the logical model used to organize and describe the data. (2) An XBRL file that defines every element that appears in a specific instance document.

external-level schema

An individual user’s view of portions of a database; also called a subschema. Contrast with conceptual-level schema and internal-level schema.

subschema

A subset of the schema; the way the user defines the data and the data relationships.

conceptual-level schema

The organization-wide view of the entire database that lists all data elements and the relationships between them. Contrast with external-level schema and internal level schema

internal-level schema

A low-level view of the entire database describing how the data are actually stored and accessed; it includes information about record layouts, definitions, addresses, and indexes. Contrast with external-level schema and conceptual-level schema.

access rights

Permissions granted to create, read, update, and delete data, database records, or data files.

data dictionary

Information about the structure of the database, including a description of each data element.

data definition language

DBMS language that builds the data dictionary, creates the database, describes logical views, and specifies record or field security constraints.

structured query language

Standardized commercial programming language designed for managing data in relational database systems. Even though it is standardized, variations exist among different database systems.

data manipulation language

DBMS language that changes database content, including data element creations, updates, insertions, and deletions.

data query language

High-level, English-like, DBMS language that contains powerful, easy-to-use commands that enable users to retrieve, sort, order, and display data.

report writer

DBMS language that simplifies report creation; users specify which data elements they want to print, and the elements are printed in the user-specified format.

data model

An abstract representation of database contents.

relational data model

A two-dimensional table representation of data; each row represents a unique entity (record) and each column is a field where record attributes are stored. Foreign keys can contain null values; when customers pay cash, Customer # in the sales table can be blank.

primary key

Database attribute, or combination of attributes, that uniquely identifies each row in a table; used to distinguish, order, and reference records in a database.

foreign key

An attribute in a table that is also a primary key in another table; used to link the two tables.

update anomaly

Improper database organization where a nonprimary key item is stored multiple times; updating the item in one location and not the others causes data inconsistencies.

insert anomaly

Improper database organization that results in the inability to add records to a database.

delete anomaly

Improper organization of a database that results in the loss of all information about an entity when a row is deleted. If customer addresses are stored in the sales table, then deleting the row where the only sale to a customer is stored results in the loss of all information for that customer. The solution is to have a sales table and a customer table and link the two tables.

entity integrity rule

A nonnull primary key ensures that every row in a table represents something and that it can be identified.

referential integrity rule

Foreign keys which link rows in one table to rows in another table must have values that correspond to the value of a primary key in another table.

normalization

Following relational database creation rules to design a relational database that is free from delete, insert, and update anomalies.

semantic data modeling

Using knowledge of business processes and information needs to create a diagram that shows what to include in a fully normalized database (in 3NF).