如何在具有一列作为 json 值的 postgres 数据库中进行查询

Question

I have a table named Test and in that one column (Subject) contains JSON values.

This is the query which i am using

select Name,Subject 
from Test 
where id =1;

And the following are the JSON values present inside table.

{
   "subject":{
      "Maths":"20",
      "Physics":"21",
      "English":"22"
   },
   "Staff":{
      "English":"Anna",
      "maths":"Rahul",
      "Physics":"John"
   }
}

Now my question is how to write a query to get English mark from JSON value. Expected o/p is 22. I am new to postgres, can any one help me in this thanks in advance

Answer 1

You can combine the -> and ->> operators

select Name,Subject, subject -> 'subject' ->> 'English' as english_mark
from Test 
where id =1;

Alternatively use the #>> operator where you provide the path to the element you want as an array of keys:

select Name,Subject, subject #>> '{subject, English}' as english_mark
from Test 
where id =1;