Query builder output for a report is undefined for a Google Cloud SQL DB but working out fine on ClearBD on Heroku

Question

I am trying to generate a csv report which is later mailed to the recipient. The CSV is generated by using node-query builder ORM. The resulting CSV is perfectly generated in an environment with my server on Heroku+ClearDB SQL but fails with the error

TypeError: Cannot read property 'length' of undefined

The code portion is as follows:

db.qb.order_by('school_order.school_id', 'desc').distinct()
     .select_avg('school_order.student_quality_price', 'average_price')
     .select('student_quality.student_quality_name, school_order.unit, school_order.marks_percent,' + 
             'school_order.fee_amount, school_order.total_marks, school_order.total_value, school_order.po_created_at')
     .where({ 'school_order.student_quality_id': matArray, 'school_order.teacher_id': supArray })
     .from('school_order')
     .join('student_quality', 'school_order.student_quality_id=student_quality.student_quality_id')
     .join('supplier', 'supplier.teacher_id=school_order.teacher_id').group_by(' student_quality.student_quality_name').get(function (err, poRes) {

          var outputpo = []

          console.log("PORESS" + poRes)

          if (poRes.length > 0) {
              poRes.forEach(po => {
              var poDate = new Date(po.po_created_at.toLocaleString()).getTime();
          if (poDate >= startDate.getTime() && poDate <= endDate.getTime()) {
              outputpo.push(po);
          }
    });

}

EDIT Database Connection

var db_settings = {
    user: `user`,
    password: `password`,
    database: `database`,
    port:port#,

    socketPath: `INSTANCE_STRING`
};
var qb = require('node-querybuilder').QueryBuilder(db_settings, 'mysql', 'single');
module.exports.qb = qb;

qb here is the querybuilder variable. In my logs, console.log("PORESS" + poRes) returns "PORESSUndefined".

Answer 1

Solved The issue was with the GROUP BY clause which some SQL versions make mandatory to include aggregated columns post the GROUP BY clause. More details here: https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html