SQL: Inner join help for assessment - mysql

Question

On my controlled assessment in school I'm stuck on this question:
Create, run, test, explain and demonstrate scripts to do the following:
Produce a list of all entries with the OCR exam board, showing:
the names of the students with entries
the subject names and level of entry for the exams the students are entered for.
Produce a list of all students, showing the students’ names, followed by the exams to be
taken. This list should be presented in alphabetical order by the student’s last name.
In my code, I don't know how to join more than 2 tables with INNER JOIN, but if I try to the 'ON' statement doesn't want to work, I don't know how to solve this question.
CREATE tables and INSERT data:
CREATE TABLE IF NOT EXISTS students
(
student_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
first_name VARCHAR(20) NOT NULL,
middle_name VARCHAR(20),
last_name VARCHAR(40) NOT NULL,
email VARCHAR(60) NOT NULL,
password CHAR(40) NOT NULL,
reg_date DATETIME NOT NULL,
PRIMARY KEY (student_id),
UNIQUE (email)
);
INSERT INTO students (first_name,last_name,email,password,reg_date) VALUES
("ex1","ex1.1","example1#gmail.com","11062001",'2009-12-04 13:25:30'),
("ex2","ex2.2","example2#gmail.com","ex123",'2015-02-12 15:20:45'),
("my name is jeff","21","kid","mynameis21kid#vine.com","yolo",'2014-09-21 14:15:25'),
("Mr.Right","Mr.Calvin","Mr.Hildfiger","Mr.misters#mister.com","mistermaster",'2015-06-04 19:50:35'),
("Bob","Dabuilda","bobthebuilder#fixit.com","BTBCWFI?",'2005-11-12 21:20:55');
CREATE TABLE IF NOT EXISTS subjects
(
subject_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
subject_name VARCHAR(20) NOT NULL,
level_of_entry VARCHAR(5) NOT NULL,
exam_board VARCHAR(10) NOT NULL,
PRIMARY KEY (subject_id),
UNIQUE(subject_id)
);
INSERT INTO subjects (subject_name,level_of_entry,exam_board) VALUES
("Chemistry","AS","OCR"),
("Biology","GCSE","AQA"),
("Music","GCSE","Edexcel"),
("English","A","OCR"),
("Physics","A","AQA"),
("Computing","GCSE","Edexcel"),
("French","A","AQA"),
("Maths","AS","OCR"),
("Product Design","GCSE","AQA"),
("History","AS","OCR");
CREATE TABLE IF NOT EXISTS entries
(
entry_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
date_of_exam DATE NOT NULL,
student_id INT UNSIGNED NOT NULL,
subject_id INT UNSIGNED NOT NULL,
FOREIGN KEY (student_id) REFERENCES students(student_id),
FOREIGN KEY (subject_id) REFERENCES subjects(subject_id),
PRIMARY KEY (entry_id)
);
INSERT INTO entries (date_of_exam, student_id, subject_id) VALUES
('2015-05-31', 1, 6),
('2015-05-31', 2, 10),
('2015-01-21', 3, 3),
('2015-01-21', 4, 7),
('2015-09-13', 5, 1),
('2015-09-13', 2, 9),
('2015-12-06', 4, 8),
('2015-12-06', 1, 2),
('2015-04-01', 3, 5),
('2015-04-01', 5, 4);
And the SELECT:
SELECT entries.*, subjects.subject_name, subjects.level_of_entry
FROM subjects
INNER JOIN entries,
students ON entries.subject_id = subjects.subject_id
WHERE subjects.exam_board LIKE "OCR%";

Answer 1

Provide the join condition right after the join to keep it simple and readable. As jarlh wrote, do not mix the explicit joins with the comma separated list. There is no need to do a like with pattern matching if you know the exact value you are looking for. Just use the = operator with the exact value.
SELECT *
FROM subjects
INNER JOIN entries ON entries.subject_id = subjects.subject_id --join 2 tables
INNER JOIN students ON entries.student_id=students.student_id --join the 3rd tables
WHERE subjects.exam_board = "OCR";

Answer 2

Use explicit JOIN's, start now and never look back! Also use aliases to keep things neat.
SELECT e.*, su.subject_name, su.level_of_entry
FROM subjects su
INNER JOIN entries e ON e.subject_id = su.subject_id
INNER JOIN students st ON e.student_id = st.student_id
WHERE su.exam_board LIKE "OCR%";

Answer 3

What I think you might need the code to look like is this:
select entries.*, subjects.subject_name, subjects.level_of_entry
from entries
join students on students.student_id = entries.student_id
join subjects on subjects.subject_id = entries.subject_id
where exam_board = 'OCR';
I hope this helps.