8.2

Consider the RDF representation of information from the university schema as shown in Figure 8.3. Write the following queries in SPARQL.

1. Find the titles of all courses taken by any student named Zhang.

2. Find titles of all courses such that a student named Zhang takes a section of the course that is taught by an instructor named Srinivasan.

3. Find the attribute names and values of all attributes of the instructor named Srinivasan, without enumerating the attribute names in your query.

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1. Find the titles of all courses taken by any student named Zhang.

select ?title 
where { 
    ?student_id         name            "Zhang"
    ?student_id         takes           ?section_id
    ?section_id         sec_course      ?course_id
    ?course_id          title           ?title
}

2. Find titles of all courses such that a student named Zhang takes a section of the course that is taught by an instructor named Srinivasan.

select ?title 
where {
    ?student_id         instance-of     student 
    ?student_id         name            "Zhang"
    ?instructor_id      instance-of     instructor 
    ?instructor_id      name            "Srinivasan"
    ?student_id         takes           ?sec
    ?instructor_id      teaches         ?sec
    ?sec                sec_course      ?course_id
    ?course_id          title           ?title
}

3. Find the attribute names and values of all attributes of the instructor named Srinivasan, without enumerating the attribute names in your query.

select ?attribute_name, ?attribute_value 
where {
    ?instructor_id      instance-of         instructor 
    ?instructor_id      name                "Srinivasan"
    ?instructor_id      ?attribute_name     ?attribute_value
}

Note that unlinke in SQL, the predicate in a triple pattern can be a variable, which can match any relationship or attribute name.