SELECT
prereq_subj,
prereq_course,
student_course_history.pidm
FROM
UTI_CUSTOM.COURSE_CATALOG_PREREQ
LEFT JOIN
uti_custom.student_course_history
    ON student_course_history.subj = prereq_subj
    AND student_course_history.numb = PREREQ_COURSE
INNER JOIN uti_custom.student_enrollment_by_term
    ON student_enrollment_by_term.pidm = student_course_history.pidm
    AND student_enrollment_by_term.term = '201901'
    AND student_enrollment_by_term.enrolled = 'Y'