Moodle get SQL data but don't get all - sql

Question

I'm working on a plugin for showing all users completed courses.
But I only get 10 records, when I place the SQL inside my database I get 40+. I think there is a limit or it does only return 1 course from every user.
Any tips?
externallib.php file:
/**
* External Web Service Template
*
* #package specialist_in_websites
* #copyright 2011 Moodle Pty Ltd (http://moodle.com)
* #license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
require_once($CFG->libdir . "/externallib.php");
class specialist_in_websites_users_courses_external extends external_api
{
/**
* Returns description of method parameters
* #return external_function_parameters
*/
public static function hello_world_parameters()
{
return new external_function_parameters(
array()
);
}
/**
* Returns welcome message
* #return string welcome message
*/
public static function hello_world()
{
global $DB;
$sql = 'SELECT u.id as user_id, c.id as course_id, DATE_FORMAT(FROM_UNIXTIME(p.timecompleted),"%Y-%m-%d") AS completed_time
FROM mdl_course_completions AS p
JOIN mdl_course AS c ON p.course = c.id
JOIN mdl_user AS u ON p.userid = u.id
WHERE c.enablecompletion = 1 ORDER BY u.id';
$datas = $DB->get_records_sql($sql);
return (array)$datas;
}
/**
* Returns description of method result value
* #return external_description
*/
public static function hello_world_returns()
{
return new external_multiple_structure(
new external_single_structure(
array(
'user_id' => new external_value(PARAM_INT, 'user id'),
'course_id' => new external_value(PARAM_INT, 'course id'),
'completed_time' => new external_value(PARAM_TEXT, 'Time of Completed'),
)
)
);
}
}
and response code:
string(510) "[{"user_id":2,"course_id":12,"completed_time":null},{"user_id":3,"course_id":10,"completed_time":null},{"user_id":4,"course_id":9,"completed_time":null},{"user_id":5,"course_id":41,"completed_time":null},{"user_id":6,"course_id":14,"completed_time":null},{"user_id":7,"course_id":10,"completed_time":null},{"user_id":8,"course_id":9,"completed_time":null},{"user_id":9,"course_id":9,"completed_time":null},{"user_id":10,"course_id":10,"completed_time":null},{"user_id":11,"course_id":10,"completed_time":null}]"

Answer 1

As stated in the docs the $DB->get_records_*() functions get a hashed array of records, indexed by the first field returned.
So, if you return more than one record with the same user_id field, then they will overwrite the previous record in the array.
Make sure you turn on debugging when developing for Moodle and you will see warning messages about this.
Solutions - either find a different field to be the first field returned (e.g. course_completions.id) or use $DB->get_recordset_sql() and then loop through the results.
Also, do not use the 'mdl_' prefix in your code, as that will break on any site with a different prefix, or if you try to run any behat or unit tests on your site. As stated in the docs, write:
FROM {course_completions} p
JOIN {course} c ON p.course = c.id
etc.
(and don't use AS with tables, as that's not compatible with all DB types)