Schemas Integration - Information Systems Reengineering, Integration and Normalization - page 265

Case 1 conflict occurs when an attribute appears as an entity in another schema.
Case 2 conflict occurs where a key appears as an entity in another schema, and case
3 conflict occurs when a component key appears as an entity in another schema. To
verify case 1, since the translation process has preserved the information capacity
in both the original schema A and the schema B into the transformed schema A = (A,
R(A, A'), A'), the transformed schema A has proved to dominate original schemas.
The transformation process is information preserved. This transformation mapping
between schema A and schema B resolves conflicts on data types since schema B
remains in its original structure. The verification of case 2 and case 3 is similar for
all cases that are transforming entity with attributes as an entity in another schema.
The only difference is the cardinality between the created entity A' and the original
entity (Fig. 7.2 ).

5XOH
,)[ ∈ DWWULEXWH$ ∩ HQWLW\%
7+(1HQWLW\$¶ ← HQWLW\%VXFKWKDWFDUGLQDOLW\$$¶ ← Q
(/6(,)[ ∈ NH\V$ ∩ HQWLW\%
7+(1HQWLW\$¶ ← HQWLW\%VXFKWKDWFDUGLQDOLW\$$¶ ←
(/6(,)[ ⊂ NH\V$ ∩ HQWLW\%
7+(1HQWLW\$¶ ← HQWLW\%VXFKWKDWFDUGLQDOLW\$$¶ ← PQ

Substep 1.3. Resolve conflicts on key.
The conflict exists where a key appears as a candidate key in another schema.
The verification of this rule is subject to the users' input. Users will have to decide
on whether schema B dominates schema A. If so, schema A will take the key of
schema B as its own key, or vice versa. Hence, this translation process is informa-
tion capacity preserved and bidirectional (Fig. 7.3 ).

7UDQVIRUPHG6FKHPD$

6FKHPD$ 6FKHPD%

&$6(

Q

$ [ & D & [ ! & D 5 & [

7UDQVIRUPHG6FKHPD$

6FKHPD$ 6FKHPD%

&$6(

$ [ & D & [ ! & D 5 & [

7UDQVIRUPHG6FKHPD$

6FKHPD$ 6FKHPD%

&$6(

$ [ Q

P

& D & [ ! & D 5 & [

$ \ $ \

Fig. 7.2 EER model with data types conflicts in three cases