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Revised Example of SQL-Query based Approach
From RDB2RDF
A sample relational schema:
deptno NUMBER UNIQUE dname VARCHAR2(30) loc VARCHAR2(100)
empno NUMBER PRIMARY KEY ename VARCHAR2(100) job VARCHAR2(30) deptno NUMBER REFERENCES DEPT(deptno) etype VARCHAR2(30)
A mapping specification (for mapping the above relational schema to RDF):
This example includes
o rdf:type columns o destination graphs (either at class-level or at instance-level) o inverse functions
Note: Expansion for prefixes "dept:" and "emp:" have not been shown.
Mapping specification (expressed using an XML-based syntax)
<?xml version="1.0" ?> <rdb2rdf_sample xmlns:xyz="http://xyz.com" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<ClassMap ClassName="xyz:dept" GraphName="xyz:DeptGraph"> <SQLdefString> Select '<xyz.com/dept/' || deptno || '>' AS deptURI , deptno , dname , loc from dept </SQLdefString> <InstURIPropertyMap DBColumnName="deptURI" /> <PropertyMap PropertyName="dept:deptno" DBColumnName="deptno" /> <PropertyMap PropertyName="dept:Name" DBColumnName="dname" /> <PropertyMap PropertyName="dept:location" DBColumnName="loc" /> <KeyMap KeyName="dept:c_unq_deptno" KeyType="Unique"> <KeyDef> <PropertyName name="dept:deptno" /> </KeyDef> </KeyMap> </ClassMap>
<ClassMap ClassName="xyz:emp"> <SQLDefString> Select '<xyz.com/emp/' || empno || '>' AS empURI , empno , ename , '<xyz.com/emp/job/'|| job || '>' AS jobTypeURI , job , deptno , '<xyz.com/emp/etype/'|| etype || '>' AS empTypeURI , etype , '<xyz.com/graph/'|| job || '/' || etype || '>' AS graphURI from emp </SQLDefString>
<InstURIPropertyMap DBColumnName="empURI" />
<RDFTypeURIPropertyMap RDFTypeURIPropertyName="emp:jobtype" DBColumnName="jobTypeURI" /> <RDFTypeURIPropertyMap RDFTypeURIPropertyName="emp:emptype" DBColumnName="empTypeURI" />
<GraphURIPropertyMap GraphURIPropertyName="emp:destGraph" DBColumnName="graphURI" />
<PropertyMap PropertyName="emp:empno" DBColumnName="empno" /> <PropertyMap PropertyName="emp:Name" DBColumnName="ename" /> <PropertyMap PropertyName="emp:job" DBColumnName="job" /> <PropertyMap PropertyName="emp:deptNum" DBColumnName="deptno" /> <PropertyMap PropertyName="emp:etype" DBColumnName="etype" />
<KeyMap KeyName="emp:c_prm_empno" KeyType="Primary"> <KeyDef> <PropertyName name="emp:empno" /> </KeyDef> </KeyMap>
<KeyMap KeyName="emp:c_ref_deptno" KeyType="Reference" RefKeyName="dept:c_unq_deptno"> <KeyDef> <PropertyName name="emp:deptNum" /> </KeyDef> </KeyMap>
</ClassMap>
</rdb2rdf_sample>
RDF Schema generated from the above mapping specification (for use by SPARQL query writers):
xyz:dept rdfs:subClassOf gen:SuperClass1
dept:deptno rdfs:domain gen:SuperClass1 dept:deptno rdfs:range xsd:integer dept:Name rdfs:domain gen:SuperClass1 dept:Name rdfs:range xsd:string dept:location rdfs:domain gen:SuperClass1 dept:location rdfs:range xsd:string
xyz:emp rdfs:subClassOf gen:SuperClass2
emp:empno rdfs:domain gen:SuperClass2 emp:empno rdfs:range xsd:integer emp:Name rdfs:domain gen:SuperClass2 emp:Name rdfs:range xsd:string emp:job rdfs:domain gen:SuperClass2 emp:job rdfs:range xyz:string emp:deptNum rdfs:domain gen:SuperClass2 emp:deptNum rdfs:range xsd:integer emp:etype rdfs:domain gen:SuperClass2 emp:etype rdfs:range xyz:string
emp:c_ref_deptno rdfs:domain gen:SuperClass2 emp:c_ref_deptno rdfs:range gen:SuperClass1
emp:jobtype rdfs:domain gen:SuperClass2 emp:jobtype rdfs:subPropertyOf rdf:type
emp:emptype rdfs:domain gen:SuperClass2 emp:emptype rdfs:subPropertyOf rdf:type