PostgreSql : Json Array to Rows using Lateral Join

Question

I have two following JSON Array in details field of my table and need to evaluate the query as I use in another relational table.

{
    \"city\": \"London\",         


        

Answer 1

Seems you need WITH ORDINALITY along with LEFT JOIN LATERALs to match the corresponding elements of the arrays due to the order in the arrays, respectively :

SELECT q.elm AS quantities, p.elm AS prices, 
       AVG(p.elm::float/q.elm::float) AS ratio
  FROM my_table t0
  LEFT JOIN LATERAL jsonb_array_elements(details -> 'quantities') 
    WITH ORDINALITY AS q(elm, i) ON TRUE
  LEFT JOIN LATERAL jsonb_array_elements(details -> 'prices') 
    WITH ORDINALITY AS p(elm, i) ON q.i = p.i
  LEFT JOIN LATERAL jsonb_array_elements(details -> 'dates') 
    WITH ORDINALITY AS d(elm, i) ON d.i = q.i
 WHERE t0.details ->> 'city' = 'London'   
 GROUP BY q.elm, p.elm;

Demo