Database get rid of repeated attribute - mysql

Question

So basically I have 3 tables: student, class, and enrollment.
CREATE TABLE class
(`class_name` varchar(13), `class_id` int primary key)
;
INSERT INTO class
(`class_name`, `class_id`)
VALUES
('math', 5697),
('science', 5768),
('computer', 6315),
('physical-ed', 6422),
('music', 7528),
('art', 7604),
('jrotc', 8797),
('culinary-arts', 8069)
;
CREATE TABLE student
(`student_fname` varchar(8), `student_id` varchar(11) primary key)
;
INSERT INTO student
(`student_fname`, `student_id`)
VALUES
('james', 'Vre94b3JpXO'),
('jim', 'JzqQ2zRVNm1'),
('jenny', 'xgqv9P42eYL'),
('kyle', 'QLNM0Wbyqk0'),
('kimberly', 'P2egAddWN0Q'),
('kayla', 'EGNDjWAreAy'),
('noah', 'bPeOyMMONGr'),
('nataly', '9Op53GGmqk5')
;
create table enrollment (
`no` int(10),
`student_id` varchar(11),
`class_id` int,
`semester` varchar(20),
primary key (`student_id`, `class_id`, `semester`),
foreign key (`student_id`) references student (`student_id`),
foreign key (`class_id`) references class (`class_id`)
);
insert into enrollment values
(1, 'Vre94b3JpXO', 5697, 'Fall 2015'),
(2,'JzqQ2zRVNm1', 5697, 'Fall 2015'),
(3, 'xgqv9P42eYL', 5697, 'Fall 2015'),
(4, 'JzqQ2zRVNm1', 8069, 'Fall 2014'),
(5, 'xgqv9P42eYL', 8069, 'Fall 2014');
If I follow the query:
select * from student s
join enrollment e on s.student_id = e.student_id
join class c on c.class_id = e.class_id
I would get something like this:
How could I remove the redundant column like student_id and class_id?
This question is extended from the page:
Table structure - Link one student with multiple classes id
and demo
I have been using the joining method but I couldn't get what I wanted, thanks for your help.

Answer 1

To answer this question, it might be nice to review some basics :
SELECT *
This * is to display all the columns from the table(s) you have selected
If you want to display only some columns, you have to specificly name it :
SELECT class_name, ...
But if you have some tables with the same column name, you have to specify the table name or alias :
SELECT c.class_name
FROM mytable t
INNER JOIN class c ON c.id_table = t.id

Answer 2

Just specify the columns you want to see.
select s.student_fname, s.student_id,
e.no, e.class_id, e.semester,
c.class_name,
from
student s join enrollment e
on s.student_id = e.student_id
join class c
on c.class_id = e.class_id ;

Answer 3

Something like this:
SELECT s.*
,e.no
,e.class_id
,e.semester
,c.class_name
FROM student s
INNER JOIN enrollment e ON s.student_id = e.student_id
INNER JOIN class c ON c.class_id = e.class_id
In your select you can specify each column you'd like and thus what order.
SELECT e.no
,e.class_id
If you want all columns from a table you can do that table dot star like:
SELECT s.*
As you already have in the existing query you can simply do star to get all the columns:
SELECT *
Here is a good place to start for some basic SELECT tricks: https://www.techrepublic.com/article/sql-basics-select-statement-options/
On an aside, it can be helpful to use a site like: http://poorsql.com/ to help with your SQL formatting.