/**
* Return a {@link qubaid_condition} from the values returned by {@link quiz_statistics_attempts_sql}.
*
* @param int $quizid
* @param array $groupstudents
* @param string $whichattempts which attempts to use, represented internally as one of the constants as used in
* $quiz->grademethod ie.
* QUIZ_GRADEAVERAGE, QUIZ_GRADEHIGHEST, QUIZ_ATTEMPTLAST or QUIZ_ATTEMPTFIRST
* we calculate stats based on which attempts would affect the grade for each student.
* @param bool $includeungraded
* @return \qubaid_join
*/
function quiz_statistics_qubaids_condition($quizid, $groupstudents, $whichattempts = QUIZ_GRADEAVERAGE, $includeungraded = false)
{
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $groupstudents, $whichattempts, $includeungraded);
return new qubaid_join($fromqa, 'quiza.uniqueid', $whereqa, $qaparams);
}
/**
* Generate the snipped of HTML that says when the stats were last caculated,
* with a recalcuate now button.
* @param object $quizstats the overall quiz statistics.
* @param int $quizid the quiz id.
* @param int $currentgroup the id of the currently selected group, or 0.
* @param array $groupstudents ids of students in the group.
* @param bool $useallattempts whether to use all attempts, instead of just
* first attempts.
* @return string a HTML snipped saying when the stats were last computed,
* or blank if that is not appropriate.
*/
protected function output_caching_info($quizstats, $quizid, $currentgroup,
$groupstudents, $useallattempts, $reporturl) {
global $DB, $OUTPUT;
if (empty($quizstats->timemodified)) {
return '';
}
// Find the number of attempts since the cached statistics were computed.
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql(
$quizid, $currentgroup, $groupstudents, $useallattempts, true);
$count = $DB->count_records_sql("
SELECT COUNT(1)
FROM $fromqa
WHERE $whereqa
AND quiza.timefinish > {$quizstats->timemodified}", $qaparams);
if (!$count) {
$count = 0;
}
// Generate the output.
$a = new stdClass();
$a->lastcalculated = format_time(time() - $quizstats->timemodified);
$a->count = $count;
$recalcualteurl = new moodle_url($reporturl,
array('recalculate' => 1, 'sesskey' => sesskey()));
$output = '';
$output .= $OUTPUT->box_start(
'boxaligncenter generalbox boxwidthnormal mdl-align', 'cachingnotice');
$output .= get_string('lastcalculated', 'quiz_statistics', $a);
$output .= $OUTPUT->single_button($recalcualteurl,
get_string('recalculatenow', 'quiz_statistics'));
$output .= $OUTPUT->box_end(true);
return $output;
}
/**
* Load the data that will be needed to perform the calculations.
*
* @param int $quizid the quiz id.
* @param int $currentgroup the current group. 0 for none.
* @param array $groupstudents students in this group.
* @param bool $allattempts use all attempts, or just first attempts.
*/
public function load_step_data($quizid, $currentgroup, $groupstudents, $allattempts)
{
global $DB;
$this->allattempts = $allattempts;
list($qsql, $qparams) = $DB->get_in_or_equal(array_keys($this->questions), SQL_PARAMS_NAMED, 'q');
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $currentgroup, $groupstudents, $allattempts, false);
$this->lateststeps = $DB->get_records_sql("\n SELECT\n qas.id,\n quiza.sumgrades,\n qa.questionid,\n qa.slot,\n qa.maxmark,\n qas.fraction * qa.maxmark as mark\n\n FROM {$fromqa}\n JOIN {question_attempts} qa ON qa.questionusageid = quiza.uniqueid\n JOIN (\n SELECT questionattemptid, MAX(id) AS latestid\n FROM {question_attempt_steps}\n GROUP BY questionattemptid\n ) lateststepid ON lateststepid.questionattemptid = qa.id\n JOIN {question_attempt_steps} qas ON qas.id = lateststepid.latestid\n\n WHERE\n qa.slot {$qsql} AND\n {$whereqa}", $qparams + $qaparams);
}
/**
* Calculating count and mean of marks for first and ALL attempts by students.
*
* See : http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
* #Calculating_MEAN_of_grades_for_all_attempts_by_students
* @param int $quizid
* @param \core\dml\sql_join $groupstudentsjoins Contains joins, wheres, params for students in this group.
* @return \stdClass with properties with count and avg with prefixes firstattempts, highestattempts, etc.
*/
protected function attempt_counts_and_averages($quizid, \core\dml\sql_join $groupstudentsjoins)
{
global $DB;
$attempttotals = new \stdClass();
foreach (array_keys(quiz_get_grading_options()) as $which) {
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $groupstudentsjoins, $which);
$fromdb = $DB->get_record_sql("SELECT COUNT(*) AS rcount, AVG(sumgrades) AS average FROM {$fromqa} WHERE {$whereqa}", $qaparams);
$fieldprefix = static::using_attempts_string_id($which);
$attempttotals->{$fieldprefix . 'avg'} = $fromdb->average;
$attempttotals->{$fieldprefix . 'count'} = $fromdb->rcount;
}
return $attempttotals;
}
/**
* Calculating count and mean of marks for first and ALL attempts by students.
*
* See : http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
* #Calculating_MEAN_of_grades_for_all_attempts_by_students
* @param int $quizid
* @param array $groupstudents
* @return stdClass with properties with count and avg with prefixes firstattempts, highestattempts, etc.
*/
protected function attempt_counts_and_averages($quizid, $groupstudents)
{
global $DB;
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $groupstudents);
$selects = array();
foreach (array_keys(quiz_get_grading_options()) as $which) {
$fieldprefix = static::using_attempts_string_id($which);
$condition = quiz_report_grade_method_sql($which);
if ($condition == '') {
$case = '1';
} else {
$case = "CASE WHEN ({$condition}) THEN 1 ELSE 0 END";
}
$selects[] = "\n SUM({$case}) AS {$fieldprefix}count,\n SUM(sumgrades * {$case}) AS {$fieldprefix}total";
}
$select = join(',', $selects);
$attempttotals = $DB->get_record_sql("\n SELECT {$select}\n FROM {$fromqa}\n WHERE {$whereqa}", $qaparams);
foreach (array_keys(quiz_get_grading_options()) as $which) {
$fieldprefix = static::using_attempts_string_id($which);
$attempttotals->{$fieldprefix . 'avg'} = $attempttotals->{$fieldprefix . 'total'} / $attempttotals->{$fieldprefix . 'count'};
unset($attempttotals->{$fieldprefix . 'total'});
}
return $attempttotals;
}
