Information Technology Reference
In-Depth Information
frame model metadata is an object-relational like metadata that can specify static
data semantic as well as dynamic data operation based on four relational tables.
7.1
Schemas Integration for RDBs
In any schema integration methodology, all the database schemas have to be speci-
fied using the same data model. The proposed approach uses an extended entity
relationship (EER) data model. Therefore, the first step in the schema integration
methodology is to translate a non-EER database schema to an EER database sche-
ma.
In our approach, a successful schema integration process should require informa-
tion capacity of the original schemas to be equivalent or dominated by the trans-
formed schemas. To achieve this, we must prove that each proposed integrated pro-
cess can preserve data semantics constraints to ensure information completeness.
The following three major steps must be followed in its sequence. However, the
sequence of substeps in each major step is immaterial.
Step 1. Resolve conflicts among conceptual schema in EER models.
Substep 1.1. Resolve conflicts on synonyms and homonyms.
This step is subject to user input during the transformation process. Role, by
definition, is the functional usage of an entity. However, to define role, in the case
of synonyms, either A.x or B.x dominates one another in its data type and size. The
only trigger here is the user identification of its semantics equivalence. Similarly,
once a user has identified that the attributes are of homonyms, the data types and its
size can be redefined into a different data structure (Kwan and Fong 1999 ; Fig. 7.1 ).
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