As mentioned in other areas of this site, the database life cycle (DBLC) consists of five stages:
Monitoring, Modification, and Maintenance
In the first stage of the DBLC, Requirements Analysis
, you determine what data your database will need to hold and what tasks it
will need to perform to meet the needs of your users.
business objects: (things in the business environment that need to be represented in the database) and
business rules: (restrictions on how users perceive and use data).
In the first phase of the Logical Design stage you convert the business objects and their characteristics into
. You then create an entity-relationship (ER) diagram
that graphically represents as base tables the entities,
their attributes, and the relationships
that exist between them.
The first course in this series covered Requirements Analysis and the Logical Design
stage through the creation of the ER diagram.
The next phase in the Logical Design stage of the DBLC is to normalize
you created in the ER diagram, so you can store and retrieve information in the database efficiently.
- Entity: A single stand-alone unit or a business object about which data are stored in a database; usually synonymous with a database table.
- Attribute: A characteristic of an entity; data that identifies or describes an entity.
Usually represented as a column in a table, attributes store data values.
- entity-relationship (ER) diagram: A diagram used during the design phase of database development to illustrate
the organization of and relationships between data during database design.
- normalize: To break up large tables into smaller, more efficient tables without losing any information.
- relationship: If the same attribute occurs in more than one table, a relationship exists between those two tables.
The next lesson introduces tables, describing their role in relational theory.