MySQL 8.0

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create table process 
  (process_id 	int, Process varchar(100),	product_id int);
create table skillrequirement 
(skillreq_id 	int, process_id 	int, skill_req varchar(100));
insert into process values (1,'Process1',133);
insert into process values (2,'Process2',133);
insert into process values (3,'Process3',133);
insert into process values (4,'Process4',133);
insert into skillrequirement values(1,1,'skill1');
insert into skillrequirement values(2,1,'skill2');
insert into skillrequirement values(3,2,'skill1');
insert into skillrequirement values(4,2,'skill4');
insert into skillrequirement values(5,3,'skill1');
insert into skillrequirement values(6,1,'skill3');
insert into skillrequirement values(7,3,'skill2');
SELECT p.product_id,
p.process,
GROUP_CONCAT(s.skill_req) AS skill_req
FROM process p
JOIN skillrequirement s
ON p.process_id = s.process_id 
WHERE p.product_id =133
GROUP BY p.process;


product_id
process
skill_req


133
Process1
skill1,skill2,skill3

133
Process2
skill1,skill4

133
Process3
skill1,skill2


SELECT p.product_id,
p.process,
GROUP_CONCAT(s.skill_req) AS skill_req
FROM process p
LEFT JOIN skillrequirement s
ON p.process_id = s.process_id 
WHERE p.product_id =133
GROUP BY p.process;


product_id
process
skill_req


133
Process1
skill3,skill2,skill1

133
Process2
skill4,skill1

133
Process3
skill2,skill1

133
Process4
null


SELECT p.product_id,
p.process,
GROUP_CONCAT(s.skill_req ORDER BY s.skill_req) AS skill_req
FROM process p
LEFT JOIN skillrequirement s
ON p.process_id = s.process_id 
WHERE p.product_id =133
GROUP BY p.process;


product_id
process
skill_req


133
Process1
skill1,skill2,skill3

133
Process2
skill1,skill4

133
Process3
skill1,skill2

133
Process4
null

product_id	process	skill_req
133	Process1	skill1,skill2,skill3
133	Process2	skill1,skill4
133	Process3	skill1,skill2

product_id	process	skill_req
133	Process1	skill3,skill2,skill1
133	Process2	skill4,skill1
133	Process3	skill2,skill1
133	Process4	null