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<< Click to Display Table of Contents >> Introduction |
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This product uses a relational database to hold the data that it requires. Within a relational database, data that are similar are kept in containers called tables. A relational database is a set of one or more related tables. Tables are made up of one or more columns containing zero or more rows.
Each table in the database holds information about a specific thing, such as trucks, customers or materials. Each table has one or more columns, and each column contains a specific type of data, such as a number, a sequence of characters (for text), or a date.
A typical fragment of a table containing customer information may look as follows:
New terminology
You may already be comfortable with the using the terms file, record, and field to describe the parts of a database. These terms are typically used to describe a flat file database. This type database typically consists of a number of files each holding information about a specific thing (customers for example). Each file contains one or more rows and each row is made up of on or more fields.
In a relational database, a table is the equivalent of a file, row is the equivalent of a record and column is the equivalent of a field.
Characteristics of relational tables
The tables of a relational database have some important characteristics:
| • | There is no significance to the order of the columns or rows |
| • | Each row contains one and only one value for each column |
| • | Each value for a given column has the same data type |