Using GROUP_CONCAT in Mysql Queries - mysql

Question

I have five tables in my database that I am working with. Everything works well till I start selecting states from the database using group concat.
These are my tables:
main_jobs
sub_jobs
category
state
state_job_relationship
Snippet of my table creation
create table if not exists category (
id int(3) not null auto_increment,
parent int(5) not null,
name varchar(255) not null,
description text,
slug varchar(255),
level int (3),
PRIMARY KEY (id, slug));
create table if not exists state (
id int(4) not null auto_increment,
country_id int(11) not null,
name varchar(255) not null,
PRIMARY KEY (id),
FOREIGN KEY (country_id) REFERENCES country (id))";
create table if not exists state_job_relationship (
id int(4) not null auto_increment,
state_id int(4) not null, FOREIGN KEY (state_id) REFERENCES state (id),
job_id int(11) not null, FOREIGN KEY (job_id) REFERENCES sub_jobs (id),
PRIMARY KEY (id));
create table if not exists main_jobs (
id int not null auto_increment, primary key(id),
company_name varchar(255),
job_title varchar(255));
create table if not exists sub_jobs (
id int not null auto_increment, primary key(id),
parent_id int(11) not null, FOREIGN KEY (parent_id) REFERENCES main_jobs (id),
title varchar(255),
description text not null,
category int (3), FOREIGN KEY (category) REFERENCES category (id)
);
This is what I want to select:
The job titles from the sub jobs tables, with the corresponding company name and other details from main_jobs and category table.
All worked well till I needed to select the states each sub_job falls in this format: State1, State2, State3
select sub_jobs.id as kid, main_jobs.id as parentid,
company_name, sub_jobs.description, sub_jobs.title,
job_title, category.name as ind,
DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d,
(select group_concat(name seperator ', ')
from state_job_relationship, state
where job_id= kid
and state.id=state_job_relationship.state_id
group by state.id) states
from sub_jobs, category, main_jobs
where category.id=sub_jobs.category
and main_jobs.id=sub_jobs.parent_id
order by featured desc , $table.id desc
limit 100;
Tried the query above but it displays this error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'seperator ', ') from state_job_relationship, state where job_id= kid and state.i' at line 1
Please what am I not getting right?

Answer 1

It looks like your error is because you are using the alais kid inside of the correlated subquery. You should replace the kid with the sub_jobs.id.
Also you have seperator spelled incorrectly.
So your code will be:
select s.id as kid,
m.id as parentid,
company_name,
s.description,
s.title,
job_title,
c.name as ind,
DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d,
(select group_concat(name SEPARATOR ', ')
from state_job_relationship
inner join state
on state.id=state_job_relationship.state_id
where job_id= s.id
group by state.id) states
from sub_jobs s
inner join category c
on c.id=s.category
inner join main_jobs m
on m.id=s.parent_id
order by featured desc , $table.id desc
limit 100;
You will notice that I changed your syntax to use ANSI JOIN syntax and I am using aliasas for the tables.
The other suggestion that I have would be to use a subquery and join to the subquery:
select s.id as kid,
m.id as parentid,
company_name,
s.description,
s.title,
job_title,
c.name as ind,
DATE_FORMAT($column_date,'%a, %e %b %Y %T') as d,
st.states
from sub_jobs s
inner join category c
on c.id=s.category
inner join main_jobs m
on m.id=s.parent_id
left join
(
select job_id, state.id, group_concat(name SEPARATOR ', ') states
from state_job_relationship
inner join state
on state.id=state_job_relationship.state_id
group by state.id, job_id
) st
on st.job_id= s.id
order by featured desc , $table.id desc
limit 100;