Characteristics of Data in Database
Characteristics of Data:
Computer uses database by adopting a set of well defined rules. You should note that just like a mailing is the below figure shows that the mailing box is filled with cards, so it is a computer database filled with records. And while each card in the box may contain several lines of written information. A record in a database contains several fields of data items. Thus, a mailing box contains cards, each of which has several lines of information on it.
Similarly, a database contains records, each of which in turn has fields in it. Assume that each in the mailing box has five lines of data items, namely,
Then, all these fields are combined to form a record. We shall now understand each part of a database one by one.
The smallest piece of meaningful information in a file is called a data item or field. A data item is generally used for a group of alphanumeric characters. The above figure displays the data items (fields) in a record. NAME, LOCALITY, CITY, STATE, and PIN_CODE are all known as data items or fields.
The collection of related fields is called a record. For example, The above figure shows that it contains six records and each record has five related fields namely, NAME, LOCALITY, CITY, STATE, and PIN_CODE.
File is the collection of all related records. The above figure shows that the file contains the list of addresses of six friends.
Database is a collection of related files. The above figure shows that the Employees database has related files containing records of employees.
In above figure, File 1 contains employee records with fields Emp_Code and Address. File 2 contains employee records with fields Emp_code and Salary. File 3 contains employee records with fields Emp_code and Name. All three files have one common field called the keyfield. It is used for identifying and relating records. The key field in a record is a unique data item which is used to identify the record to access and manipulate the database.