Field (computer science)

 ( Data Modeling ) 

In data hierarchy, a field ( data field) is a variable in a record.

A record, also known as a data structure, allows logically related data to be identified by a single name. Identifying related data as a single group is central to the construction of understandable .

(2026). 9780201710120, Addison-Wesley. ISBN 9780201710120

The individual fields in a record may be accessed by name, just like any variable in a computer program.

(2026). 9780201710120, Addison-Wesley. ISBN 9780201710120

Each field in a record has two components. One component is the field's data type declaration. The other component is the field's identifier.

---

Memory fields Fields may be stored in random access memory (RAM). The following Pascal record definition has three field identifiers: firstName, lastName, and age. The two name fields have a datatype of an array of character. The age field has a datatype of integer. type PersonRecord =

   record
       lastName : array [ 1 .. 20 ] of Char;
       firstName : array [ 1 .. 20 ] of Char;
       age : Integer
   end;
     

In Pascal, the identifier component precedes a colon, and the datatype component follows the colon. Once a record is defined, variables of the record can be allocated. Once the memory of the record is allocated, a field can be accessed like a variable by using the dot notation. var alice : PersonRecord; alice.firstName := 'Alice';

Over time, the term field has been replaced with the terms data member

and attribute.

(2026). 9780201710120, Addison-Wesley. ISBN 9780201710120

The following Java class has three attributes: firstName, lastName, and age. public class PersonRecord {

private String firstName;
private String lastName;
private int age;
     

}

---

File fields Fields may be stored in a random access computer file.

(2026). 9780201710120, Addison-Wesley. ISBN 9780201710120

A file may be written to or read from in an arbitrary order. To accomplish the arbitrary access, the operating system provides a method to quickly seek around the file.

(1984). 9780139376993, Prentice Hall. ISBN 9780139376993

Once the disk head is positioned at the beginning of a record, each file field can be read into its corresponding memory field.

File fields are the main storage structure in the ISAM (ISAM). In relational database Database theory, the term field has been replaced with the terms column and attribute.

---

See also

Post Comment