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up vote 0 down vote favorite

My postgres db version: 9.4.4. and I have a table with this structure;

CREATE TABLE product_cust
(
 productid character(2),
  data jsonb,
)

I have records like this in the "data" column;

{"productid":"01","cust": [
        {"cell": ["0000xxx0", "0000xxx1"], "name": "John", "email": ["[email protected]"], "custtype": "c"}, 
        {"cell": ["0000xxx2", "0000xxx3"], "name": "Smith", "email": ["[email protected]"], "custtype": "c"}  
]}

I need to extract all records for "cell" . Expected record will be 

["0000xxx0", "0000xxx1","0000xxx2", "0000xxx3"]

or for "email" ["[email protected]","[email protected]"]

My best effort below has been a two(2) step process and will not scale for x no of "cust" objects;

select (data::json#>'{cust,0}')::json#>'{cell}' from product_cust; //return "0000xxx0", "0000xxx1"
select (data::json#>'{cust,1}')::json#>'{cell}' from product_cust; //return "0000xxx2", "0000xxx3"

I will be most grateful if i can be pointed in the right direction

share|improve this question
up vote 2 down vote accepted

Use json_agg() and jsonb_array_elements() functions:

select json_agg(cell)
from (
    select jsonb_array_elements(elem->'cell') cell
    from (
        select jsonb_array_elements(data->'cust') elem
        from product_cust
        ) subsub
    ) sub

You can merge two inner subqueries:

select json_agg(cell)
from (
    select jsonb_array_elements(jsonb_array_elements(data->'cust')->'cell') cell
    from product_cust
    ) sub

Group results by productid:

select productid, json_agg(cell)
from (
    select productid, jsonb_array_elements(jsonb_array_elements(data->'cust')->'cell') cell
    from product_cust
    ) sub
group by 1
order by 1
share|improve this answer
    
real grateful, you have definitely pointed me there, will read on those links. Can you update your query to group by productid, so that for each "productid",there are the associated "cell" – BlowMan Sep 14 '15 at 18:44
    
Already done ;) – klin Sep 14 '15 at 18:47
    
Wow, superfast, super klin!! – BlowMan Sep 14 '15 at 18:50

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