Text search in PostgreSQL: How to order rows by column - sql

Question

I have a table with people's three desired job positions, ranked from first to third.
The job positions are in a separate table called "job_positions":
job_position_id job_position_title
1 bar manager
2 barista
3 waiter
4 server
The "people" table contains the person_id with the IDs of the job positions they have chosen.
person_id first_position_id second_position_id third_position_id
1 1 2 3
2 2 4
I want to search this table for a job position and order the results so that the person who has that job in their first_position, will be ranked higher than those who have it in their second or third position.
So in this example, if I search for "barista", I expect the person_id 2 to be displayed first, then person_id 1.
This is my SQL code:
SELECT person_id
TS_RANK_CD(TO_TSVECTOR('english', a.job_position_title), query_first, 1) AS first,
TS_RANK_CD(TO_TSVECTOR('english', b.job_position_title), query_second, 1) AS second,
TS_RANK_CD(TO_TSVECTOR('english', c.job_position_title), query_third, 1) AS third
FROM people
LEFT JOIN job_positions a
ON people.first_position_id = a.job_position_id
LEFT JOIN PHRASETO_TSQUERY ('barista') AS query_first
ON TO_TSVECTOR ('english', a.job_position_title) ## query_first
LEFT JOIN job_positions b
ON people.second_position_id = b.job_position_id
LEFT JOIN PHRASETO_TSQUERY ('barista') AS query_second
ON TO_TSVECTOR ('english', b.job_position_title) ## query_second
LEFT JOIN job_positions c
ON people.third_position_id = c.job_position_id
LEFT JOIN PHRASETO_TSQUERY ('barista') AS query_third
ON TO_TSVECTOR ('english', c.job_position_title) ## query_third
WHERE (TO_TSVECTOR (a.job_position_title) ## query_first OR TO_TSVECTOR (b.job_position_title) ## query_second OR TO_TSVECTOR (c.job_position_title) ## query_third)
The SQL returns the correct matches, but not ranked like they should be. Can I add some kind of score/weight to the columns, to rank them by that score?

Answer 1

I replicated your case with
create table job_positions (job_position_id int, job_position_title varchar);
insert into job_positions values (1, 'bar manager');
insert into job_positions values (2, 'barista');
insert into job_positions values (3, 'waiter');
insert into job_positions values (4, 'server');
create table people (person_id int, first_position_id int, second_position_id int, third_position_id int);
insert into people values (1,1,2,3);
insert into people values (2,2,4,NULL);
If I understand you correctly you want to order based on the position, if that is true, you can simply solve the problem with the following
with unpivoting as (
select person_id, 1 as position, first_position_id as job_position_id from people UNION ALL
select person_id, 2 as position, second_position_id as job_position_id from people UNION ALL
select person_id, 3 as position, third_position_id as job_position_id from people
)
select job_position_title, unpivoting.job_position_id, position, person_id from unpivoting join job_positions on unpivoting.job_position_id = job_positions.job_position_id order by unpivoting.job_position_id, position, person_id;
with the expected result
job_position_title | job_position_id | position | person_id
--------------------+-----------------+----------+-----------
bar manager | 1 | 1 | 1
barista | 2 | 1 | 2
barista | 2 | 2 | 1
waiter | 3 | 3 | 1
server | 4 | 2 | 2
(5 rows)

Answer 2

You want to unpivot the job preferences for each user. In fact, you might want to store the data in the unpivoted way -- which is more commonly called normalized.
In Postgres, you can use a lateral join to unpivot:
select p.*
from people p cross join lateral
(values (1, p.first_position_id),
(2, p.second_position_id),
(3, p.third_position_id)
) v(ord, job_position_id) join
job_positions jp
using (job_position_id)
where jp.job_position_title = ?
order by v.ord;