Displaying results from multiple tables SQL/PHP - php

Question

I currently have a database with 12 tables. I am doing a php query to pull the information from the database but I am not getting anything displayed. The query alone bridges all the tables starting with table schedule that have a foreign key related. Should I need to start the query from the table class and bridge with other tables?
TABLE DESIGN- PICTURE
If you like to duplicate my design- QUERY
$query = ("SELECT class_name, class_caption, class_credit_hours, class_description
FROM schedule
INNER JOIN section
ON class.id = section.class_id
INNER JOIN faculty
ON faculty.id = section.faculty_id
INNER JOIN faculty
ON faculty.id = office_hours.faculty_id
INNER JOIN faculty_titles
ON faculty_titles.faculty_id = faculty.id
INNER JOIN faculty_education
ON faculty_education.faculty_id = faculty.id
INNER JOIN section
ON section.faculty_id = faculty.id
INNER JOIN class
ON class.id = section.class_id
INNER JOIN major_class_br
ON major_class_br.class_id = class.id
INNER JOIN major_minor
ON major_class_br.major_minor_id = major_minor.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_description'] . "<br>";
print $row ['class_credit_hours'] . "hrs. <br>";
print "------------------------------<br />";
$totalhours += $row['class_credit_hours'];
}
}
SQL fiddle query

Answer 1

SELECT class_name, class_caption, class_credit_hours, class_description
FROM schedule
INNER JOIN section
ON class.id = section.class_id
Right here there's a problem: you are doing a INNER JOIN using the field 'class.id' but the table 'class' isn't in either side of the JOIN. So it won't work.
The query should start like this:
SELECT class_name, class_caption, class_credit_hours, class_description
FROM class
INNER JOIN section
ON class.id = section.class_id
And then do the JOIN with the table 'schedule' with the table it shares a common index (I guess it would be class).
The complete query should be something like this:
SELECT class.class_name, class.class_caption, class.class_credit_hours, class.class_description
FROM class
INNER JOIN section
ON class.id = section.class_id
INNER JOIN faculty
ON faculty.id = section.faculty_id OR faculty.id = office_hours.faculty_id
INNER JOIN faculty_titles
ON faculty_titles.faculty_id = faculty.id
INNER JOIN faculty_education
ON faculty_education.faculty_id = faculty.id
INNER JOIN major_class_br
ON major_class_br.class_id = class.id
INNER JOIN major_minor
ON major_class_br.major_minor_id = major_minor.id
INNER JOIN sched_sect_br
ON sched_sect_br.section_id = section.id
INNER JOIN schedule
ON schedule.id = sched_sect_br.schedule_id
INNER JOIN semester
ON semester.id = schedule.semester_id
INNER JOIN office_hours
ON schedule.id = office_hours.schedule_id AND faculty.id = office_hours.faculty_id
This query gets info from all the tables you have in your graph, aside from the event table, that isn't related to any other. But still this query should have more fields on the SELECT (you are only selection fields from the class table, I understand you'd want data from the other 10 tables as well), to do this simple add 'tablename.field' to the list of fields from the SELECT.