postgresql bulk update

bulk_update.sql

CREATE TABLE billing.mytable(id integer, name text);

INSERT INTO billing.mytable VALUES(1, '1');
INSERT INTO billing.mytable VALUES(2, '2');
INSERT INTO billing.mytable VALUES(3, '3');

UPDATE billing.mytable
SET name = Q.name
FROM (
         SELECT (value->>0)::integer AS id, (value->>1)::decimal AS name
         FROM json_array_elements('[[1, "100"], [2, "200"]]')
     ) Q
WHERE mytable.id = Q.id;

SELECT * FROM billing.mytable;