Select from Multiple table, but ignore if not found - php

Question

Using this query I'm selecting rows from multiple tables. Unfortunately, if a row does not exist in one table, then rows in all tables won't return. It's because I'm using AND operator.
So, I want this query to be modified, where will ignore a table if value is not found, but return rest of the tables where the value is found.
Here's the MySQL query:
foreach ($courseArr as $term) {
$term = trim($term);
if (!empty($term)) {
$courseSectionSql[] = "courseDataApp.course = '$term' AND courseDataApp.section = '$sectionArr[$i]'";
$i++;
}
}
$data = $db->rawQuery("SELECT courseDataApp.*, facultyDatabase.*, books.*
FROM courseDataApp
INNER JOIN facultyDatabase ON facultyDatabase.initial = courseDataApp.faculty
INNER JOIN books ON books.course = courseDataApp.course WHERE ".implode(' OR ', $courseSectionSql));
Here's what is returns:
{
"id":11,
// courseDataApp values
"faculty":"AKH1",
"course":"CSE241",
"section":"7",
.
.
.
.
.
.
.
// facultyDatabasevalues
"initial":"AKH1",
"name":"Ms. Kamal Habi",
"dept":"ECE",
.
.
.
.
.
.
// books values
"books": "Digital Logic Design"
},
So the problem is, when a value from facultyDatabase or books tables not found, rest of the data won't return. I just want it to ignore that, show what's found. Like Union.

Answer 1

As some of the comments point out you are using outdated syntax that INNER JOINs the tables which leads to the result you get. You need to LEFT JOIN the tables. Hence you will have a result even though there are no entries in the LEFT JOINed tables. Something like this should work
SELECT courseDataApp.*, facultyDatabase.*, books.*
FROM courseDataApp
LEFT JOIN facultyDatabase ON facultyDatabase.initial = courseDataApp.faculty
LEFT JOIN books ON books.course = courseDataApp.course
WHERE courseDataApp.course = '$term'
AND courseDataApp.section = '$sectionArr[$i]'
Written like this you would have an equivalent to your query in current syntax that will not return anything if there are no entries in the INNER JOINed tables.
SELECT courseDataApp.*, facultyDatabase.*, books.*
FROM courseDataApp
INNER JOIN facultyDatabase ON facultyDatabase.initial = courseDataApp.faculty
INNER JOIN books ON books.course = courseDataApp.course
WHERE courseDataApp.course = '$term'
AND courseDataApp.section = '$sectionArr[$i]'