Database Reference
In-Depth Information
Director_thesis
Dir-id
Integer
Dir_lastname
String
Dir-name
String
Lab_id
Laboratory
Foreign_Student
IS-A
St_id
Student
Laboratory
Student
Country
String
St_id
St_name
St_lastname
Integer
Lab-id
Lab-name
Lab-adress
Integer
String
String
String
String
Dir_id
Director_thesis
Part_of
Thesis_hasStudent
Part_of
Thesis_hasLab
Thesis
St-id
Th-id
Supported
Student
Th_id
Th_name
Topic
Integer
Thesis
Boolean
String
String
Dir_id
Director_thesis
Fig. 9.15 Hypernode database schema
Considering the initial database, Fig. 9.15 shows the resulting hypernode
schema.
9.4.1.2 Data Conversion
In order to instantiate the hypernode database schema already identified, data
conversion is performed in three steps. First, the relational database table's tuples
are extracted. Second, these data are converted to match the target format. Then, for
each hypernode in the hypernode database, a set of instances hypernode HI is
extracted from the relational tuples.
The set of instances hypernode HI is defined by HI
¼
H i n
f
H i : ¼h
h, h i ;
N hi i
g;
where:
l H i denotes the instance hypernode
l h denotes the hypernode source name
l h i denotes the name of H i
l N hi denotes a set of nodes N hi
:¼f
n
n
n i
:¼ <
n n ;
t
;
val
>g
, where n n is the node
name, t is the type, and val mentions the node value
For each relation in the LHD , a set of instance rel ations RI is extracted using the
value of keys on the relational tables. RI is defined by RI
:¼f
r i n
r i
:¼h
r
;
h is ;
h id ig
,
where:
l r denotes the relation which is intanciated by r i
l h is denotes the hypernode instance source
l h id denotes the hypernode instance destination
Search WWH ::




Custom Search