BIS 261 - Chapter 9 - Database Modeling and Design

composite attribute

- an attribute that has meaningful component parts

range control value

- may have a limited set of permissible values - numerical AND alphabetic data

referential integrity

- one of the most important principles of the relational model - NOT a way to build a data model that has the properties of simplicity, nonredundancy, and minimal maintenance - example: cross-referencing between relations

database model examples

- relational model - hierarchical model - network model - NOT matrix model

de-normalization

- spliting shit

hashed file organization

- the location of each ROW is determined by an algorithm

relation

- the sequence of columns can be interchanged without changing the meaning or use of the relation - a named, two-dimensional table of data and each relation (or table) consists of a set of named columns and an arbitrary number of unnamed rows - each relationship in an E-R diagram must be represented in the relational database design - is NOT in first normal form if every nonprimary key attribute is functionally dependent on the whole primary key - each column corresponds to an attribute of that relation

default value

- the value a field will assume unless an explicit value is entered for the field

logical database modeling and design

- translate conceptual E-R data model for the application or enterprise - developed without explicit consideration of specific user interfaces, into normalized data requirements. - view integration - results: normalized relations - you must account for every data element on a system input or output form or report and on the E-R diagram - typically performed in parallel with PHYSICAL database design other systems design steps

T or F: Physical table design and normalization have the same goals.

False

indexed file organization

- a file organization in which rows are stored either sequentially or non-sequentially, and an index is created that allows software to locate individual rows.

physical table

- a named set of rows and columns that specifies the fields in each row of the table - NOT the same goals as normalization

normalization

- a process for converting complex data structures into simple, stable data structures

foreign key

- an attribute that appears as a non-primary key attribute in one relation and as a primary key attribute (or part of a primary key) in another relation

physical file

a named set of table rows stored in a contiguous section of secondary memory

synonyms

- two or more attributes may have different names but the same meaning, as when they describe the same characteristic of an entity - when merging relations that contain synonyms, you SHOULD choose a third name to replace the synonyms

view integration

we combine normalized data requirements from all user interfaces into one consolidated logical database model

To convert a relation to second normal form, you decompose the relation into new relations using the attributes, called ________, that determine other attributes.

determinants

primary key

example: driver's license number (very unique)