A software application that allows for the management of data and information structured as fields, records and files. Database programs provide a way of creating and manipulating the electronic equivalent of a name and address card that can hold large amounts of information.
Because all data are structured into a one- record-per-subject or one-record-per-transaction format, it allows for powerful query capabilities, in which you can select records based on any of their content. A database program is the heart of a business information system and provides mainly file creation, data entry, update, query and reporting functions.
The traditional term for a database program is a database management system (DBMS). It is also called a "data management system." For more details on the features of a DBMS, see
DBMS. Also see
application software for a breakdown of all major software applications.
User Interaction with a Database Program
The database programs available for Windows and Mac let you perform all the following tasks interactively on one file at a time. However, as soon as you want data in one file to automatically update another, programming has to be done. That is where the faint of heart take their leave, and the hackers take over. Following are the common tasks you need to perform to create and work with a database file.
Create a File and Set Index Order
Each field in a record is defined by name, type and length. In order to keep the file in sequence, one or more fields are defined as key fields, upon which indexes are created and maintained. The index is updated whenever new records are added or existing records are deleted or any data in a key field changes.
Create Data Entry Forms
Data entry is accomplished by designing a form to display each record. Data entry forms contain field validation. You decide what data can go in and what must stay out of these fields.
Update/Edit
In a single-user, one-file-at-a-time application, there is nothing to predefine here. Changing data is just a matter of opening the file and selecting the EDIT mode. However, in a multiuser system, security must be administered and audit trails must be programmed.
View/Query
You can browse an entire file or just selected records. Selected records are usually created as a temporary file that can be saved or abandoned. The temporary file may be sorted into a new sequence if desired.
The ease with which a query can be composed determines how much users will ask their own questions or rely on their IT staff to create them. Getting data from two files; for example, customers and orders, or vendors and purchases, requires knowledge of how to link the files for the query. Most database programs have a JOIN function, which creates a new file with data from two existing files. Once a query description has been composed, it can be saved for use again.
Reporting
Reports provide details and summaries in a more elaborate fashion than queries. They have page and column headers and can be sorted into order by multiple fields; for example, county within city within state. Once a report description has been composed, it can be saved for use again.
Modify Structure
From time to time, it is necessary to add or delete fields, or change their lengths or possibly their names. This function is similar to creating the record structure in the first place, except that you are editing the structure rather than defining it from scratch.