gistfile1.rb

Student.joins(:classrooms).where(classrooms: { school_id: [15975, 692, 296] }).each do |s|
  s.student_settings[:scantron_username] ||= (s.username.length > 16 ? s.username[0..11] + (rand() * 9999).to_i.to_s.rjust(4, '0') : s.username)
end

gistfile2.sql

SELECT DISTINCT ON(s.id)
  cu.name as "Customer",
  coalesce(d.name,'No District') as "District",
  sc.name as "School",
  c.name as "Classroom",
  u.first_name || ' ' || u.last_name as "Teacher",
  u.email as "Teacher Email",
  s.username as "Student TTM Username",
  scantron_username as "Student Scantron Username",
  (CASE WHEN s.username = scantron_username THEN true ELSE false END) as "Username matches?",
  s.first_name as "First Name",
  s.last_name  as "Last Name",
  g.number as "Current Grade"
FROM
  students s
  join grade_levels g on g.id = s.grade_level_id
  left join classroom_students cs on cs.student_id = s.id
  left join classrooms c on cs.classroom_id = c.id
  left join schools sc on sc.id = c.school_id
  left outer join districts d on sc.district_id = d.id
  left join customers cu on cu.id = sc.customer_id
  left join classroom_teachings ct on ct.classroom_id = c.id
  left join users u on u.id = ct.user_id
  join (
    SELECT
      ss.thing_id as student_id,
      (regexp_matches(ss.value, '[\w\d]+'))[1] as scantron_username
    FROM
      student_settings ss
    WHERE
      ss.var = 'scantron_username'
  ) ss on ss.student_id = s.id
WHERE
  s.is_active
  AND c.name not like 'Temp Upload%'
  AND sc.id IN (
    16537, 16376, 16144, 16127, 16150, 16135, 16129, 16138, 16133, 16139, 16125, 16128, 16118, 16136, 16140, 16142, 16308, 16311, 1796 --ID
    4714, 4697, 4721, 4611, 4684, 4726, 4792, --TX
    14644, 14633, 16848, 12814, 12368, 12366, 12416, 14620, 12550, 14846, 12145, 15038, 12512, 12481, 14615, 12365, 12376 --OK
    15984, 14148, 15983, 15974, 15975, 15978, 13887  --UT
  )
;

gistfile3.sql

SELECT DISTINCT ON(s.id)
  '73-7012-7820' as "Site ID",
  (regexp_matches(ss.value, '[\w\d]+'))[1] as "Student ID",
  s.first_name as "First Name",
  s.last_name  as "Last Name",
  '' as "Middle Initial",
  '' as "Date Of Birth",
  '' as "Gender",
  g.number as "Current Grade",
  '' as "Ethnicity",
  '' as "Citizenship",
  '' as "LEP",
  '' as "Migratory Child",
  '' as "MEP",
  '' as "SMEP",
  '' as "Student With Disability",
  '' as "Title I",
  '' as "Meal Assist",
  '' as "IEP",
  '' as "Test Password",
  '' as "Reading Start",
  '' as "Math Start",
  '' as "Science Start",
  '' as "Language Start",
  '' as "Enrollment Date",
  '' as "Algebra Start",
  '' as "Reading Foundation Start"
FROM
  students s
  join grade_levels g on g.id = s.grade_level_id
  join student_settings ss on ss.thing_id = s.id AND ss.var = 'scantron_username'
  join classroom_students cs on cs.student_id = s.id
  join classrooms c on cs.classroom_id = c.id
  join schools sc on sc.id = c.school_id
  join customers cu on cu.id = s.customer_id
  join states st on st.id = cu.state_id
WHERE
  s.is_active
  AND st.code IN ('UT')
  ;