How a Specification for a Field Will Be Determined

Nazneen (2009) explains, “Field type depicts the data type of the field”.
For example, a relationship may not be established or may not function correctly if we have selected Number as a field type for the primary key attribute and Text field type is selected for the foreign key attribute.
3. Why are field values coded or compressed?
A coded field represents a corresponding value stored in a separate relation. Coded fields serve several different purposes, which depends on their implementation. Usually coded fields are introduced to save time and space in RDBMS.
For example, we have a code_employee_type attribute in a relation. This field will be populated depending on the selection of a combo box item, named as an employee category on a data entry form.
4. What means are available to control the integrity of fields?
The integrity of the field ensures the entry of predefined data types and formats in an attribute. A user is bound to enter data incorrect data type and format while entering using Data Entry Form. There are several tools available, which restricts incorrect data entry or in some cases, users can only select from the available list of items/values in a List, Combo, Radio or Checkbox control, etc.
5. How can possible missing field values be handled?
Blank or missing fields are those fields where a record does not contain any data. Missing fields can be avoided by introducing compulsory data entry controls, but it is often impossible or undesirable because of user convenience and usability considerations. Missing fields can be populated on-the-fly by default values or in some cases by using auto-increment specifications.
6. Why might normalize relations not translate into efficient physical records?
Normalized tables usually do not translate into efficient physical records because normalization decomposes larger tables into smaller ones and the query generates a record based on the unique field in all related tables. Hernandez observes the fact and states, “The physical order of the record or field in a table is completely immaterial and each record in a table is identified by a field that contains a unique value” (2003).