What is a Database?
A database is an organized set or collection of related data that is stored in a file. The data in a database is entered in as records that consist of items or fields of data. Everyone has a database- take a look at your address book. An address book is a set of related information about a person (his name, telephone number and perhaps their address, fax number etc.). It is also organized - it is sorted alphabetically by name.
Each record is essentially a row of related information. Each field within the record contains information that pertains to that record. For example, a telephone directory can be considered a database. Each record has specific and unique information. The following fields or columns of information would typically be found in a telephone directory: first name, last name, address, and city and telephone number.
The following example shows a sample database:
Last Name, First Name, Address, City and Telephone are columns within the database table and are called Field Names. In other words, they identify the type of data shown in the columns below. First Name is the field name while John, Joan and Nancy are fields within individual records. Each row or record holds unique information. Only John Smith lives at 302 Milton Street in Indianapolis and has the telephone # 876-2256. In this case, the unique field would be telephone number.
A relational database allows you to create smaller and more manageable files that can be joined to extract or compare data on an as needed basis because the data in one file is linked to another via a unique field.
A database management system (DBMS) controls the structure of a database and access to the data. In other words, it creates, manages and protects that data as well as providing access, which also allows the user to integrate and share data across several files.