Merge multiple rows into one with more than one row value in a column

Question

I'm currently building a query to retrieve some data from my db, I need to access some information with a common id in just one row.

With this query:

select 
        missions_answer.response_id as "response",
        crm_player."document" as "document",
        missions_question.label as "label",
        missions_answertext.body as "bill #",
        missions_answerselectmultiple.body as "product",
        missions_answerinteger.body as "answer" 
from missions_answer 
    left join missions_question on missions_answer.question_id = missions_question.id 
    left join missions_answertext on missions_answer.id = missions_answertext.answer_ptr_id 
    left join missions_answerselectmultiple on missions_answer.id = missions_answerselectmultiple.answer_ptr_id
    left join missions_answerinteger on missions_answer.id = missions_answerinteger.answer_ptr_id 
    left join missions_response on missions_answer.response_id = missions_response.id
    left join crm_player on missions_response.player_id = crm_player.id
    LEFT JOIN crm_user ON crm_player.user_id = crm_user.id
    where  missions_answer.response_id = '71788176'
    group by missions_answer.response_id, crm_player.document,missions_answertext.body,
        missions_question.label,
        missions_answerselectmultiple.body ,
        missions_answerinteger.body,
        crm_user.first_name,
        crm_user.last_name

This is what I currently have:

+   response    +     document    +    label    +    bill #  +    product  +  answer
-   71788176    -     79907201    -    bill #   -    26899   -             -
-   71788176    -     79907201    -    amount   -            -             -    1
-   71788176    -     79907201    -    product  -      -    {"name": "Shoes"}   -
-   71788176    -     79907201    -    price    -            -             -  25.99

This is what I'm looking for:

+   response    +     document    +    bill #  +    product  +  amount  +   price 
-   71788176    -     79907201    -    26899   -     shoes   -       1  -   25.99 

I've been trying to use crosstab but I'm still unable to find it, thanks in advance for any hint or help.

Answer 1

From your current state you simply can do the pivot using the FILTER clause:

demo:db<>fiddle

SELECT
    response,
    document,
    MAX(bill) FILTER (WHERE label = 'bill') as bill,
    MAX(answer) FILTER (WHERE label = 'amount') as amount,
    MAX(product) FILTER (WHERE label = 'product') as product,
    MAX(answer) FILTER (WHERE label = 'price') as price
FROM t
GROUP BY response, document

---

I am not quite sure, how your original table looks like. If it is more like this:

response | document | label   | value
-------: | -------: | :------ | :----
71788176 | 79907201 | bill    | 26899
71788176 | 79907201 | amount  | 1    
71788176 | 79907201 | product | shoes
71788176 | 79907201 | price   | 25.99

Then you can modify the query like this:

demo:db<>fiddle

SELECT
    response,
    document,
    MAX(value) FILTER (WHERE label = 'bill') as bill,
    MAX(value) FILTER (WHERE label = 'amount') as amount,
    MAX(value) FILTER (WHERE label = 'product') as product,
    MAX(value) FILTER (WHERE label = 'price') as price
FROM t
GROUP BY response, document

---

Edit : TO added the JSON value to product column:

demo:db<>fiddle

Variant 1: You could simply cast the type json into type text :

MAX(product::text) FILTER (WHERE label = 'product') as product,

Variant 2: You read the value from the "name" attribute:

MAX(product ->> 'name') FILTER (WHERE label = 'product') as product,