从JSON PostgreSQL提取

Question

I have three columns:

• id,
• state,
• curr_status

The curr_status column has data that's formatted like this:

[{"id": 123, "created_at": "2017-07-17T19:49:19.125865", "status": "student"}]

I want to SELECT id, state, and extract the status for each row into a new column so it says student. New to working with JSON, how would I write the code to do that?

Answer 1

You didn't specify what should happen if the array contains more than one element.

But to get the value for the first array element, you can use the -> operator to get the first array element, then use the ->> operator to get

select id, state, 
       curr_status -> 0 ->> 'status' as status
from the_table;

Answer 2

One option would be using json_array_elements function which firstly will split the elements of the array and then filter :

select id , state, js ->> 'status' as st_special
  from tab, --> your table with columns id, state, curr_status(of type json)
       jsonb_array_elements(curr_status) as js
 where js ->> 'status' = 'student';

Demo