You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20180719143617_fix_wrong_school_calendar_classroom_steps.rb
    path of file: ./repos/i-diario/db/migrate
    
    the code of the file until where you have to start completion: class FixWrongSchoolCalendarClassroomSteps < ActiveRecord::Migration[4.2]
  def change
    execute <<-SQL
      DELETE FROM descriptive_exams
      WHERE NOT EXISTS(
        SELECT 1
          FROM descriptive_exam_students AS des
        WHERE des.descriptiv
    
  def change
    execute <<-SQL
      DELETE FROM descriptive_exams
      WHERE NOT EXISTS(
        SELECT 1
          FROM descriptive_exam_students AS des
        WHERE des.descriptive_exam_id = descriptive_exams.id
      );

      UPDATE descriptive_exams
          SET school_calendar_classroom_step_id = (
          SELECT MAX(sccsa.id)
              FROM school_calendar_classrooms AS scca
              JOIN school_calendar_classroom_steps AS sccsa
                ON sccsa.school_calendar_classroom_id = scca.id
            WHERE scca.classroom_id = descriptive_exams.classroom_id
              AND sccsa.start_at BETWEEN sccs.start_at AND sccs.end_at
              AND sccsa.end_at BETWEEN sccs.start_at AND sccs.end_at
        )
        FROM school_calendar_classroom_steps AS sccs
        JOIN school_calendar_classrooms AS scc
          ON scc.id = sccs.school_calendar_classroom_id
        WHERE sccs.id = descriptive_exams.school_calendar_classroom_step_id
          AND scc.classroom_id <> descriptive_exams.classroom_id;

      DELETE FROM conceptual_exams
      WHERE NOT EXISTS(
        SELECT 1
          FROM conceptual_exam_values AS cev
        WHERE cev.conceptual_exam_id = conceptual_exams.id
      );

      UPDATE conceptual_exams
          SET school_calendar_classroom_step_id = (
          SELECT MAX(sccsa.id)
              FROM school_calendar_classrooms AS scca
              JOIN school_calendar_classroom_steps AS sccsa
                ON sccsa.school_calendar_classroom_id = scca.id
            WHERE scca.classroom_id = conceptual_exams.classroom_id
              AND conceptual_exams.recorded_at BETWEEN sccsa.start_at AND sccsa.end_at
        )
        FROM school_calendar_classroom_steps AS sccs
        JOIN school_calendar_classrooms AS scc
          ON scc.id = sccs.school_calendar_classroom_id
        WHERE sccs.id = conceptual_exams.school_calendar_classroom_step_id
          AND scc.classroom_id <> conceptual_exams.classroom_id;

      UPDATE school_term_recovery_diary_records
          SET school_calendar_classroom_step_id = (
          SELECT MAX(sccsa.id)
              FROM school_calendar_classrooms AS scca
              JOIN school_calendar_classroom_steps AS sccsa
                ON sccsa.school_calendar_classroom_id = scca.id
            WHERE scca.classroom_id = rdr.classroom_id
              AND rdr.recorded_at BETWEEN sccsa.start_at AND sccsa.end_at
        )
        FROM recovery_diary_records AS rdr,
              school_calendar_classroom_steps AS sccs,
              school_calendar_classrooms AS scc
        WHERE rdr.id = school_term_recovery_diary_records.recovery_diary_record_id
          AND scc.classroom_id <> rdr.classroom_id
          AND sccs.id = school_term_recovery_diary_records.school_calendar_classroom_step_id
          AND scc.id = sccs.school_calendar_classroom_id;
    SQL
  end