我正在做一个 sql 查询，但它没有从表中返回任何数据。我不知道为什么，我已经从INNERtoLEFT但没有运气。我已经多次修改查询，但我找不到问题。关于为什么我没有得到任何显示的任何想法？
PHP
$query = ("SELECT class.class_name, class.class_caption, class.class_credit_hours, class.class_description, faculty_fname, faculty_lname
FROM class
LEFT JOIN section
ON class.id = section.class_id
LEFT JOIN faculty
ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id
LEFT JOIN faculty_titles
ON faculty_titles.faculty_id = faculty.id
LEFT JOIN faculty_education
ON faculty_education.faculty_id = faculty.id
LEFT JOIN major_class_br
ON major_class_br.class_id = class.id
LEFT JOIN major_minor
ON major_class_br.major_minor_id = major_minor.id
LEFT JOIN sched_sect_br
ON sched_sect_br.section_id = section.id
LEFT JOIN schedule
ON schedule.id = sched_sect_br.schedule_id
LEFT JOIN semester
ON semester.id = schedule.semester_id
LEFT JOIN office_hours
ON schedule.id = office_hours.schedule_id AND faculty.id = office_hours.faculty_id
");
//execute query
$result = mysql_query($query);
if ($result){
$totalhours = 0;
while ($row = mysql_fetch_assoc( $result ))
{
print "<b>" . $row['class_name'] . "</b><br>";
print $row['class_caption'] . "<br>";
print $row ['class_credit_hours'] . "hrs. <br>";
print $row ['faculty_lname'] . "hrs. <br>";
print $row ['faculty_fname'] . "hrs. <br>";
print $row['class_description'] . "<br>";
print "------------------------------<br />";
$totalhours += $row['class_credit_hours'];
}
}
print "<p>Total hours for Major: " . $totalhours . ".</p>";
所需显示：
Computer Programming I
CP1000
4
James Doe
This course offers introduction to programming.
更新：问题在这里找到，但我不知道为什么
ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id