Defining and Naming Fields:

Field Definitions: When defining a field, we need to take the following into consideration:

a)       Breaking up the field into their component parts. For example, we might break, EMP_NAME into EMP_FNAME and EMP_LNAME. 

b)       The chosen data-type and its size should represent all possible values. For example, taking ROLL_NUM number(2) will limit the maximum value to be ‘99’.

c)       There should be one unique record-identifier (primary key) in each table. For example, ROLL_NUM is a unique record-identifier

Naming Conventions: When naming a field, we need to take the following into consideration:

a)       The field names should be as descriptive as possible. For example, a field name like ENM is not descriptive; on the other hand, a field name like EMP_NUM is self descriptive.

b)       The filed name should be as short as possible. For example, taking a field name as LIB_RENEW_DATE is more advisable than taking a lengthy field name like STUDENT_LIBRAY_CARD_RENEWAL_DATE.

c)       It should take necessary prefixes. For example, Fields of ‘Employee’ table may take the prefix EMP as in EMP_NUM, EMP_NAME, EMP_CITY and so on.