SQL Distinct pairs matched on array of strings - sql

Question

This is a simplified version of the tables but I have a table called NAME with 2 columns, names (strings) and classes (strings)
index
name
classes
0
Joe
Mat 12
1
Hector
Mat 12
2
Terry
Arc 13
3
Elizabeth
Soc 7
4
Wyatt
Arc 13
5
Alex
His 9
6
James
Mat 12
7
Rebecca
Soc 7
NOTE: All names and classes actually have a numerical ID associated with them, used actual names for illustration.
I want to pair up unique people taking the same class, with the output table looking something like this.
name1
name2
class
Joe
Hector
Mat 12
Joe
James
Mat 12
Hector
James
Mat 12
Terry
Wyatt
Arc 12
Worth noting is that the output table should have unique pairs and a person shouldn't be paired with themselves (so don't want outcome like this)
name1
name2
class
Joe
Hector
Mat 12
Hector
Joe
Mat 12
Joe
Joe
Mat 12
I've tried something along the lines of
SELECT NAME.names as name1, NAME.names as name2, NAME.classes as c1, COUNT(*) as pa
FROM NAME
JOIN NAME
ON name1.c1 = name2.c1
GROUP BY name1, name2
ORDER BY c1
But doesn't work.

Answer 1

You may achieve this using a join and comparison based on the index/name
Query #1
SELECT
n1.name as name1,
n2.name as name2,
n1.classes
FROM
NAME n1
INNER JOIN
NAME n2 ON n1.classes=n2.classes AND n1.index < n2.index;
name1
classes
name2
Joe
Mat 12
Hector
Terry
Arc 13
Wyatt
Joe
Mat 12
James
Hector
Mat 12
James
Elizabeth
Soc 7
Rebecca
Query #2
SELECT
n1.name as name1,
n2.name as name2,
n1.classes
FROM
NAME n1
INNER JOIN
NAME n2 ON n1.classes=n2.classes AND n1.name < n2.name;
name1
classes
name2
Hector
Mat 12
Joe
James
Mat 12
Joe
Terry
Arc 13
Wyatt
Hector
Mat 12
James
Elizabeth
Soc 7
Rebecca
View on DB Fiddle
Let me know if this works for you.