Domain And Attributediginame buy new website by csc
it is important to appreciate the difference between in doman on the one hand and columns are attributes which are dropped from the domain on the other attributes represent the use of domains within relations to emphasize the distinctions we may get attributes name that are distinct from those of the underlying domains .
DOMAIN. PART NUMBER CHARACTER
DOMAIN PART NAME CHARACTER
DOMAIN COLOR. CHARACTER
DOMAIN. WEIGHT. CHARACTER
DOMAIN. LOCATION. CHARACTER
P#. : DOMAIN PART_NUMBER
PNAME. : DOMAIN PART_NAME
COLOR. : DOMAIN COLOR
WEIGHT. : DOMAIN WEIGHT
CITY. :. DOMAIN LOCATION
B A PART OF RELATIONS SCHEMA IN WHICH 5 DOMAIN ( PART ,NUMBER PART NAME ,DOMAIN COLOR,DOMAIN WEIGHT, AND DOMAIN LOCATION )ONE OF RELATIONSHIP (P# , PNAME, COLOUR, WEIGHT, CITY ,)HAVE BEEN DECLARED .
EACH ATTRIBUTE IS SPECIFIED AS BEING DRAW FROM A CORRESPONDENT DOMAIN THE SCHEMA WRITTEN IN A HYPOTHETICAL DATA DEFINITION LANGUAGE.
We shall very often make use of a convention that allow us to omit the specification of the domain from in an attribute declaration if the attribute bears the same name however it is not allowed possible to do this.
we have a relation with three attribute but only two distinct domains .the meaning of tuple of the relations component is the major part include the minor part in the indicated quantity as an immediate component that two distinct domain and quantity.
Example illustrate another common convention date of generating distinct attributes name why prefixing a common domain name with distinct role name to indicated the district rule being played by that domain in each of its appearances.