What SQL Statements Will Normalize and Cleanse this table - postgresql

Question

What we are trying to achieve is some level of cleansing on the table. This is what we currently have (this a subset of the table please)
+-----------+------------+-----------+------------+--------+-----------+------------+-------+
| STUDENTNO | LASTNAME | FIRSTNAME | PREFERNAME | GENDER | COURSE | YEAR | MAJOR |
+-----------+------------+-----------+------------+--------+-----------+------------+-------+
| auaw64 | Drury | Janet | Jane | f | DIPLOMA | 29/10/2011 | NO |
| auaw64 | Drury | Janet | Jane | f | BACHELORS | 29/09/2013 | YES |
| auqn70 | Givens | Jason | | m | DIPLOMA | 29/10/2011 | NO |
| auqn70 | Givens | Jason | | m | BACHELORS | 10/10/2012 | YES |
| mrpd90 | Blackstock | Williams | Bill | m | DIPLOMA | 29/10/2011 | NO |
| mrpd90 | Blackstock | Williams | Bill | m | BACHELORS | 29/09/2013 | YES |
| pyts84 | Peters | Theresa | | f | BACHELORS | 29/09/2013 | YES |
| qjgp97 | Aaron | Felina | | f | DIPLOMA | 29/10/2013 | NO |
| qzhs28 | Gyeong | Ma | | f | DIPLOMA | 29/10/2011 | NO |
| qzhs28 | Gyeong | Ma | | f | BACHELORS | 29/09/2013 | YES |
| uwnv95 | Anholt | Wilhemina | | f | MASTERS | 29/10/2011 | NO |
| uwnv95 | Anholt | Wilhemina | | f | BACHELORS | 10/10/2012 | YES |
| jaiw67 | Muguruza | David | Dave | m | MASTERS | 28/09/2014 | YES |
+-----------+------------+-----------+------------+--------+-----------+------------+-------+
But we need to reorder this table with the 'studentno' as the new primary key and then perform an update/upsert (which is where the new columns have now emerged)
+-----------+------------+-----------+------------+--------+--------------+------------+--------------+------------+
| STUDENTNO | LASTNAME | FIRSTNAME | PREFERNAME | GENDER | MAJOR_COURSE | MAJOR_YEAR | MINOR_COURSE | MINOR_YEAR |
+-----------+------------+-----------+------------+--------+--------------+------------+--------------+------------+
| auaw64 | Drury | Janet | Jane | f | BACHELORS | 29/09/2013 | DIPLOMA | 29/10/2011 |
| auqn70 | Givens | Jason | | m | BACHELORS | 10/10/2012 | DIPLOMA | 29/10/2011 |
| mrpd90 | Blackstock | Williams | Bill | m | BACHELORS | 29/09/2013 | DIPLOMA | 29/10/2011 |
| pyts84 | Peters | Theresa | | f | BACHELORS | 29/09/2013 | null | null |
| qjgp97 | Aaron | Felina | | f | DIPLOMA | 29/10/2013 | null | null |
| qzhs28 | Gyeong | Ma | | f | BACHELORS | 29/09/2013 | DIPLOMA | 29/10/2011 |
| uwnv95 | Anholt | Wilhemina | | f | BACHELORS | 29/09/2013 | DIPLOMA | 29/10/2011 |
| jaiw67 | Muguruza | David | Dave | m | MASTERS | 28/09/2014 | null | null |
+-----------+------------+-----------+------------+--------+--------------+------------+--------------+------------+
Essentially we want to take the first table and convert to the second but doing this using the functionalities inside PostgreSQL and also turning the 'studentno' into the unique key. We can then write the new table into another for another app to read or make use of but the new key will now offer a proper query handle unlike we have in the original table.

Answer 1

First create the course table
CREATE TABLE Courses (
id SERIAL,
course varchar);
Then insert all courses into the new table
insert into Courses(course)
select course from Participants GROUP BY course
Then create the n-n relation table
CREATE TABLE Participants_Courses (
id SERIAL,
studentno varchar,
course integer,
year date,
major boolean);
Then insert the values from Participants into the n-n table
INSERT INTO Participants_Courses AS PC (studentno, course, year,major)
VALUES (SELECT STUDENTNO, (SELECT id FROM Courses AS C where PC.course = C.course), YEAR, MAJOR);
Finally drop the unnecessary columns from the Participants table
ALTER TABLE Participants DROP COLUMN course;
ALTER TABLE Participants DROP COLUMN year;
ALTER TABLE Participants DROP COLUMN major;
This is normalized, I would not recommend to insert two courses into the same column of the table, because it would limit you. With this, a person could have many courses.
This is the Third normal form, see https://en.wikipedia.org/wiki/Third_normal_form
I did not test the SQL's so there may be syntax errors ;)

Answer 2

Disclaimer:
Doing this is completely backwards and wrong. It's doubling down on a bad table design by making it into a worse one. Do not use wide, denormalized tables as your primary data store.
Read:
https://en.wikipedia.org/wiki/Normalization
https://en.wikipedia.org/wiki/Third_normal_form
and get familiar with using joins.
If you use this solution then I am sorry to whoever has to maintain the code later. You appear to be determined to do it, and there are legitimate reasons you might want to make this transformation for things like a view or report, so here's how.
Use a self-left-join, treating studentno as the key. Something like:
select
l."STUDENTNO", l."LASTNAME", l."FIRSTNAME", l."PREFERNAME", l."GENDER",
l."COURSE" AS "MAJOR_COURSE", l."YEAR" AS "MAJOR_YEAR",
r."COURSE" AS "MINOR_COURSE", r."YEAR" AS "MINOR_YEAR"
FROM table1 l
LEFT OUTER JOIN table1 r
ON (l."STUDENTNO" = r."STUDENTNO"
AND (l."COURSE", l."YEAR") <> (r."COURSE", r."YEAR"))
WHERE (l."COURSE", l."YEAR") < (r."COURSE", r."YEAR")
OR r."COURSE" IS NULL;
A proper solution wouldn't rely on the lexical sort of BACHELORS before DIPLOMA and would instead use a CASE statement or a function to produce proper ordering, but since we're already piling wrong on top of wrong, it doesn't matter much.
SQLfiddle: http://sqlfiddle.com/#!15/2f49f/1
Now. Delete this, and go do it properly. Create a STUDENT table and COURSE table, and a STUDENT_COURSE table that joins them and records which students took which courses in which years. It's relational databases 101.