Join query in Moodle only returns last column only while mysql returns correctly

Question

I have 2 tables in my moodle database such as equiz_details and equiz_responses as follows:

mdl_equiz_details:

mdl_equiz_details

I have used a join query to fetch result as desired form as follows:

SELECT distinct ed.quizid,ed.questionnumber,ed.questiontext,ed.optiontext1,ed.optiontext2,ed.optiontext3,ed.optiontext4, ed.correctanswer,er.studentanswer FROM `mdl_equiz_details` as ed INNER JOIN `mdl_equiz_responses` as er ON ed.quizid = er.quizid and ed.questionnumber = er.questionnumber and er.studentid=4 and er.quizid=25

I fired the query in mysql database annd got result as follows:

Result in mysql

I am using the same query inside my moodle page and try to fetch result as follows::

<?php
require_once('../../config.php');
global $DB; 

$quizresdetails = $DB->get_records_sql("SELECT ed.quizid,ed.questionnumber,ed.questiontext,ed.optiontext1,ed.optiontext2,ed.optiontext3,ed.optiontext4, ed.correctanswer,er.studentanswer FROM {equiz_details} ed INNER JOIN {equiz_responses} er ON ed.quizid = er.quizid and ed.questionnumber = er.questionnumber and er.studentid=4 and er.quizid=25");      

var_dump($quizresdetails);

?>

I am getting the result as follows:

Result in Moodle page

Which is obviously the last result.

What I am doing wrong? How can I fetch full result in my moodle page?

Moodle version: 2.9.1

Answer 1

The problem is your query is returning the same value for its id in each record: "25". The Moodle get_records_* methods expect every result to have a unique id, as it uses that id as the array key in the array of results it returns. So it's finding all your results, but as it loops through them it is adding each result to the array key "25", so then when it gets to the end, it only has the last result in the returned array.

So you need to return a field with a unique id for each row, as "id".