Database Reference
In-Depth Information
EXTERNAL SCHEMA
CONCEPTUAL SCHEMA
AgentID
AgentName
AgentAddress
AgentPhone
PolicyHolderName
Address
Phone
AgentID
AgentName
AgentAddress
AgentPhone
PolicyNo
PolicyPeriod
PolicyStatus
DeductibleAmount
PolicyTerms
PremiumAdjustment
ClaimNo
AccidentDate
AccidentDesc
DamageDesc
DamageAmount
SettlementAmount
PolicyNo
PolicyPeriod
PolicyStatus
DeductibleAmount
PolicyTerms
Premium
PolicyHolderName
AccidentDate
AccidentDesc
DamageDesc
DamageAmount
SettlementAmount
PolicyHolderName
Address
Phone
PolicyNo
Figure 4-14
Auto insurance database: conceptual schema.
Figure 4-15 shows the components of the internal schema for the insurance data-
base. Note that the internal or physical schema is made up of data files, index files,
records, fields, and so on. Also, note how the internal schema is a translation of the
conceptual schema to the level of physical hardware. In physical storage, data exist
as files and records.
IMPLEMENTATION AND DEPLOYMENT
Before you can implement the database of your organization and deploy it for use,
you must know what you are implementing. This knowledge comes from the design.
We have noted the two types of design necessary for a database—logical and phys-
ical. We have also recognized the need for design at these two levels. We have seen
how the external schema and the conceptual schema for the database result from
the logical design process. Transformation of the conceptual schema into the inter-
nal schema results from the physical design process. Once you have the design at
the two levels, you are ready for implementation and deployment of the database.
Essentially, implementation consists of getting the data storage areas and files ready
and placing initial data in these storage files. Deployment relates to making the data-
base available to the users once the initial data is in.
Database administrators perform most of the activities in the implementation
and deployment phase. Analysts also participate in this phase, but the primary
responsibility rests with database administrators. Figure 4-16 indicates the major
activities in this phase. Note how the responsibilities for the activities are shared.
Part V of this topic covers topics on implementation and deployment of rela-
tional databases in greater detail. Therefore, at this stage of enumerating DDLC
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