Introduction to Databases
Database Structure
A database is like a filing cabinet. It can be a computer file but it doesn't have to be. It is a flexible way to store organize, reorganize, and report related information for distribution. A database file is a collection of related information. Each file stores information about one topic.
A database consists of one or more records of information. Each record is a collection of information about one person, place, or thing. A record contains all the pieces of information about a particular subject. For example, if you had a database of the people with whom you correspond, each record would contain information on one person. If your database contained twenty records, you would have information on twenty people.
Each record in a database contains different pieces of information named fields.
A field is just one component of the record and contains one item in the record. In the example of a database of people with whom you correspond, each record might have a name field, an address field, and a telephone number field.
Database Field Types
Text (or character): A text field may contain any character. In an electronic database, a numeric character designated as text may NOT be used in calculations (e.g., zip code).
Numeric: A numeric field can ONLY contain a number and may be used in calculations.
Date: A field classified as a date may be used in day/date calculations. The user may choose different date formats to suit specific information needs.
Boolean: A Boolean field is a "logical" field that can have one of two values (e.g., true or false).
Other types of fields include picture fields (for graphics), calculation fields (for mathematical manipulation of one or more fields in the same record), and summary fields (for mathematical manipulation of fields from different records).
