newerLogo3

Data Model Fundamental Components

Table Specification

A database table, defined within the database's schema (i.e., schematic), contains a name, definition, and one or more defined processes that are row (i.e., record) actions. Row actions are inserts, deletes, or modifications. The table process can commence either just before the row action, or after the row action. These row actions are also called Triggers.

Column Specification

A column (i.e., field), defined within the database's table, contains a name definition, and one or more defined processes that are column (i.e., field value) actions. Column actions are value-sets, value-deletes, or value modifications. A column process can commence either just before the column value action occurs, or after the column action occurs. All column actions are encapsulated within row actions.

Column specifications also contain data type specifications.

Primary Key Specification

A Primary Key with associated columns that enable the selection of one and only one row (record). E.g., Customer Id.

Unique Key Specification

A Unique Key with associated columns that enable the selection of one and only one row (record). E.g., Customer Name. While a Unique Key can also be considered as an Alternate Primary Key, the key designation, Primary Key, often has automatic database management system (DBMS) built in processes.

Secondary Key Specification

A Secondary Key with associated columns enable the selection of one or more rows (records). E.g., Customer City.

Foreign Key Specification

One or more Foreign Keys with their associated columns, which are really just primary keys from other (i.e., Foreign) tables. The Foreign Key’s value  serves as Source and Target relationship mechanisms. E.g., Customer Key, which is the Customer table’s Customer Id as a “foreign key” column in the Customer Address table.

For Sales and Corporate: 1-301-249-1142 Whitemarsh@Wiscorp.com

Whitemarsh Information Systems Corporation

2008 Althea Lane Bowie, Maryland 20716 USA

Copyright 1981 - 2016, Whitemarsh Information Systems Corporation
Proprietary Data, All rights Reserved