load_extension('perlvtab.so')


select a.student, b.student,
    a.Reading,
    b.subject
 from roster a inner join join_to_me b on a.student=b.student;
student|student|Reading|subject
Fred|Fred|A|Reading
Mary|Mary||Reading

create virtual table roster2
     using perl ("SQLite::VirtualTable::Pivot", "join_to_me", "student", "subject", "grade" );

select a.student, a.Writing from roster a inner join roster b
    on a.student=b.student;
student|Writing
Fred|B-
Mary|B

select a.student, a.Writing, b.Reading from roster a inner join roster b
    on a.Reading=b.Reading;
student|Writing|Reading
Fred|B-|A